Science 2005 Set 1

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Science 2005 Set 1 Close

Subjective Test(i) The question paper consists of two sections, A andB. You are to attempt both

the sections.

(ii) All questions are compulsory.

(iii) There is no overall choice. However, internal choice has been provided.

(iv) All questions ofSection A and all questions ofSection B are to be attemptedseparately.

(v) Questions number1to 5 in Section A and21to 23 in Section B are short answer

type questions. These questions carry one mark each.

(vi) Questions number6to 10in Section A and24 to 25 in Section B are short answer

type questions and carry two marks each.

(vii) Questions number11to 17in Section A and26to 29 in Section B are also short

answer type questions and carry three marks each.

(viii) Questions number18to 20in section A and question number30in section Bare long answer type questions and carryfive marks each.

Section AQuestion 1 ( 1.0 marks)

Give an example of photochemical reactions.

Question 2 ( 1.0 marks)

Name a metal which offers higher resistance to the passage of electricity than copper.


State a reaction in which SO2 acts as an oxidising agent.


Where will the image be formed by a concave mirror when an object is placed between the pole

and the focus point of the mirror?

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Which has a higher resistance: a 50 W lamp bulb or a 25 W lamp bulb and how many times?


How is plaster of Paris chemically different from gypsum? How may they be interconverted?

Write one use of plaster of Paris.


Allotropy is a property shown by which class of substances, elements, compounds or mixtures?

Give one example of allotropy.


Draw diagrams to distinguish between 'equatorial orbit' and 'polar orbit' of artificial satellites ofearth.


With respect to air, the refractive indices of water and benzene are 1.33 and 1.50 respectively.Calculate the refractive index of benzene with respect to water.


What is the cause of release of unusually large energies in nuclear fission reactions? How is the

energy per fission calculated?

OR

What is a thermal neutron? Draw a schematic diagram depicting fission of a U-235 nucleus on

absorption of a thermal neutron.


(a) State the relation between hydrogen ion concentration of an aqueous solution and its pH.

(b) The pH of an aqueous solution decreases from 3 to 2. Calculate how many times the

hydrogen ion concentration of the solution will change.


Explain the following regarding the manufacture of ammonia by Haber's process, The reaction

being;

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(i) This reaction is carried out at a high temperature even though it is an exothermic reaction.(ii) To make ammonia, the mixture of N2 and H2 gases is passed over heated iron.


(i) Distinguish between an addition polymer and a condensation polymer.(ii) Choose one condensation polymer and one addition polymer from amongst the following:nylon, teflon, neoprene, polyester

(iii) Write a chemical equation for the reaction involved in the formation of a polyamide.


(a) Write the chemical equation representing the reaction for the preparation of methanal from

methanol.

(b) What happens when methanal is mixed with:

(i) Ammoniacal silver nitrate solution and the mixture is warmed(ii) Fehling's reagent and the mixture is warmed(c) Complete the reaction equation:

CH3CHO + HCN

OR

Write the formulae for the given compounds and name the functional groups present in each ofthem:

(i) Ethanoic acid (ii) Propanone (iii) Nitromethane


A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the

energy consumed if this bulb is lighted for four hours.


Name three forms in which energy from oceans is made available for use. What are OTEC

power plants? How do they operate?


Describe briefly the Big Bang Theory of the origin of universe.


(a) Write chemical equations for the reactions involved in obtaining pure alumina from the

mineral bauxite which has impurities of iron oxide and silica.

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(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminiumfrom alumina.

OR

(a) What is corrosion of metals? Name one metal which does not corrode and one whichcorrodes on being kept in atmosphere.

(b) How will you show that the rusting of iron needs oxygen and moisture at the same time?


1. Explain the following terms used in relation to defects in vision and corrections providedfor them:

(i) Myopia (ii) Astigmatism (iii) Bifocal lenses (iv) Far sightedness(b) Describe with a ray diagram how a person with myopia can be helped by spectacles.

OR

(a)What is a 'simple microscope? Draw diagrams to show the image formed by a simplemicroscope with the eye focussed:

(i) on near point (ii) at infinity

(b)What is the maximum magnification obtainable by a simple microscope?


(a) What are 'magnetic field lines'? How is the direction of a magnetic field at a point

determined?

(b) Draw two field lines around a bar magnet along its length on its two sides and mark the fielddirections on them by arrow marks.

(c) List any three properties of magnetic field lines.

Section B


Write the expanded form of the abbreviation AIDS.


Why is one arm in sub-metacentric chromosome longer than the other?

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What is 'Green House Effect'?


What is 'eutrophication'? Write its two harmful effects.


List any four practices which help in protecting our environment.

OR

Describe any four modes of disposal of waste.


What is 'translocation'? Why is it essential for plants? Where in plants are the following

synthesized: (i) Sugars (it) Hormones

OR

What is 'clotting of blood'? Write a flow chart showing major events taking place in clotting of

blood.


Draw a diagram of human brain and label on it the following of its parts:(i) Cerebrum (ii) Meninges

(iii) Medulla Oblongata (iv) Cerebellum


Differentiate between 'self pollination' and 'cross pollination'. Describe 'double fertilization' in

plants.


What is 'organic evolution'? How do embryological studies provide evidence for evolution?


Explain the process of 'photosynthesis' in plants. List four factors which influence this process

and describe how each of them affects the rate of the photosynthesis process.

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Give an example of photochemical reactions.

Solution:

An example of photochemical reactions is the process of photosynthesis occurring in the leaves

of green plants.


Name a metal which offers higher resistance to the passage of electricity than copper.

Solution:


State a reaction in which SO2 acts as an oxidising agent.

Solution:

Sulphur dioxide oxidises hydrogen sulphide (H2S) to sulphur (S).


Where will the image be formed by a concave mirror when an object is placed between the pole

and the focus point of the mirror?

Solution:

An image will form behind the mirror when an object is placed between pole and the focus of a

concave mirror.


Which has a higher resistance: a 50 W lamp bulb or a 25 W lamp bulb and how many times?

Solution:

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The resistance of 25 W lamp bulb has a higher value as compared to that of 50 W lamp bulb.Resistance of the 25 W lamp bulb will be double of that of the 50 W lamp bulb.


How is plaster of Paris chemically different from gypsum? How may they be interconverted?Write one use of plaster of Paris.

Solution:

Plaster of Paris is calcium sulphate hemihydrate (CaSO4.H2O) while gypsum is calcium

sulphate dihydrate (CaSO4.2H2O).

Gypsum, when heated at a temperature of about 380 K, changes to plaster of Paris.

Plaster of Paris, when mixed with water, changes into hard mass called gypsum.

Plaster of Paris is used in hospitals for setting fractured bones.


Allotropy is a property shown by which class of substances, elements, compounds or mixtures?Give one example of allotropy.

Solution:

The property of allotropy is shown by the elements.

Sulphur has two allotropes rhombic sulphur and monoclinic sulphur.


Draw diagrams to distinguish between 'equatorial orbit' and 'polar orbit' of artificial satellites of

earth.

Solution:

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With respect to air, the refractive indices of water and benzene are 1.33 and 1.50 respectively.

Calculate the refractive index of benzene with respect to water.

Solution:

Refractive index of medium 1 with respect to medium 2 (21)

It is given that:

With respect to air, refractive index of water is 1.33.

With respect to air, refractive index of benzene is 1.50.

Therefore, with respect to water, refractive index of benzene = = 1.127


What is the cause of release of unusually large energies in nuclear fission reactions? How is the

energy per fission calculated?

OR

What is a thermal neutron? Draw a schematic diagram depicting fission of a U-235 nucleus on

absorption of a thermal neutron.

Solution:

Nuclear fission is a nuclear reaction where nucleus of a heavy atom splits into two lighter nuclei.

In this process, some nuclear mass gets destroyed and converted into energy. According to

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Einsteins massenergy relation, when a mass is destroyed, it gets converted into a huge amountof energy. It is the destruction of mass that is responsible for the release of unusually large

energies in nuclear fission react ions.

This part of the question is out of current syllabus.

Or

Out of current syllabus


(a) State the relation between hydrogen ion concentration of an aqueous solution and its pH.

(b) The pH of an aqueous solution decreases from 3 to 2. Calculate how many times the

hydrogen ion concentration of the solution will change.

Solution:

(a) Following is the relation between hydrogen ion concentration of an aqueous solution and its

pH.

(b) If the pH of the solution decreases from 3 to 2, then

Hence, hydrogen ion concentration will increase 10 times.


Explain the following regarding the manufacture of ammonia by Haber's process, The reaction

being;

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(i) This reaction is carried out at a high temperature even though it is an exothermic reaction.(ii) To make ammonia, the mixture of N2 and H2 gases is passed over heated iron.

Solution:

(i) Habers process for the synthesis of ammonia is carried out at a high temperature because atlow temperatures, the reaction becomes very slow due to which the rate of formation of ammoniabecomes very slow.

(ii) Heated iron acts as a catalyst in the synthesis of ammonia. It accelerates the rate of reactionand hence acts as a promoter.


(i) Distinguish between an addition polymer and a condensation polymer.

(ii) Choose one condensation polymer and one addition polymer from amongst the following:

nylon, teflon, neoprene, polyester(iii) Write a chemical equation for the reaction involved in the formation of a polyamide.

Solution:

(i) Following are the differences between an addition and a condensation polymer:

Sl.No Addition Polymers Condensation Polymers

(a) These are obtained by the additionreactions of unsaturated compounds

containing double and triple bonds.

These are obtained by the condensationreactions between two different organic

compounds (called monomers).

(b) No simple molecule such as water is

eliminated during this process.

Simple molecule such as water is eliminated

during this process.

(c) For example, polythene is an addition

polymer.

For example, polyester is a condensation

polymer.

ii. One condensation polymer is polyester.One addition polymer is teflon.

ii. Following is the chemical reaction involved in the formation of a polyamide.

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(a) Write the chemical equation representing the reaction for the preparation of methanal from

methanol.

(b) What happens when methanal is mixed with:

(i) Ammoniacal silver nitrate solution and the mixture is warmed

(ii) Fehling's reagent and the mixture is warmed(c) Complete the reaction equation:

CH3CHO + HCN

OR

Write the formulae for the given compounds and name the functional groups present in each of

them:(i) Ethanoic acid (ii) Propanone (iii) Nitromethane

Solution:

(a) The chemical equation representing the reaction for the preparation of methanal from

methanol is as follows:

(b)(i) When methanal is mixed with ammoniacal silver nitrate solution and the mixture is warmed, a

shining silver mirror is formed on the inner side of the test tube. Following is the reaction takingplace.

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(ii) When methanal is mixed with Fehling's reagent and the mixture is warmed, a red precipitateof copper (I) oxide is formed. Following is the reaction taking place.

(c)

OR

The formulae for the given compounds and the names of the functional groups present in them

are as follows:

(i) Ethanoic acid: CH3COOH

Functional group: carboxylic acid group

(ii) Propanone: CH3COCH3

Functional group: ketonic group

(iii) Nitromethane: CH3NO2

Functional group: nitro group


A torch bulb is rated 2.5 V and 750 mA. Calculate (i) its power, (ii) its resistance and (iii) the

energy consumed if this bulb is lighted for four hours.

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Solution:

It is given that:

Voltage (V) = 2.50 V

Current (I) = 750 mA = 0.75 A

The bulb is lighted for 4 hours.

Thus,

i) Power generated (P) = VI= 2.50 0.75 = 1.87 W

i) Resistance (R) = 3.33

iii) Energy consumed in 4 hours = Power Time = P t= 1.87 4 = 7.48 Wh


Name three forms in which energy from oceans is made available for use. What are OTEC

power plants? How do they operate?

Solution:

Energy from oceans is used as tidal energy, wave energy, and thermal energy.

What are OTEC power plants? How do they operate?

This question is out of current syllabus


Describe briefly the Big Bang Theory of the origin of universe.

Solution:

This question is out of current syllabus


(a) Write chemical equations for the reactions involved in obtaining pure alumina from the

mineral bauxite which has impurities of iron oxide and silica.

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(b) Draw a labelled diagram of the electrolytic tank cell used for the extraction of aluminiumfrom alumina.

OR

(a) What is corrosion of metals? Name one metal which does not corrode and one whichcorrodes on being kept in atmosphere.

(b) How will you show that the rusting of iron needs oxygen and moisture at the same time?

Solution:

(a) The reaction involved in obtaining pure alumina from the mineral bauxite having impurities

of iron oxide and silica is:

(i)

The iron oxide and silica (sand) present in the bauxite ore do not dissolve in sodium hydroxidesolution. Therefore, they are separated by filtration.

(ii)

(iii)

(b)

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OR

(a) The eating up of metals by the action of air and moisture on their surface is called corrosion.

Metal which does not corrode on being kept in the atmosphere is gold.

Metal which corrodes on being kept in the atmosphere is iron.

(b) Take three boiling tubes and label them asA,B, and C. Place clean iron nails, free

from rust, in each tube. Add water to tubeA in such a manner that some parts of the nailsare exposed to air and seal it with the help of a rubber cork. Add boiled water to tubeB in

such a way that the nails are completely submerged. Then, pour some amount of keroseneoil in the tube and seal it with the help of a rubber cork. Add anhydrous calcium chloride

to tube Cand then seal it. Leave the tubes undisturbed for two weeks and observe the

changes.

It will be observed after two weeks that the nails in tubesBandCare clean. However, the

nails in tubeAare rusted.

In tubeA, both moisture and oxygen were available and the nails started rusting after twoweeks. This shows that for rusting to take place, the presence of both oxygen and water is

essential.

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In tubeB, the iron nails were in contact only with water as oxygen was not allowed todissolve in water by the layer of oil. As the nails did not rust even after two weeks when

only water was available, it shows that rusting cannot take place if only water isavailable.

In tube C, only oxygen was present as anhydrous calcium chloride absorbed all themoisture present inside the tube. As the nails did not rust even after two weeks when onlyoxygen was available, it shows that rusting cannot take place if only oxygen is available.

Conclusion:

The rusting of iron requires both oxygen and water.


1. Explain the following terms used in relation to defects in vision and corrections providedfor them:

(i) Myopia (ii) Astigmatism (iii) Bifocal lenses (iv) Far sightedness(b) Describe with a ray diagram how a person with myopia can be helped by spectacles.

OR

(a)What is a 'simple microscope? Draw diagrams to show the image formed by a simplemicroscope with the eye focussed:

(i) on near point (ii) at infinity

(b)What is the maximum magnification obtainable by a simple microscope?

Solution:

(a)

(i)Myopia is also known as near sightedness. This means a person suffering from myopia can seenearby objects clearly, but cannot see far-off objects clearly. Image of a nearby object is formed

in front of retina for a myopic eye. This defect may be caused because of either an increase insize of the eyeball or excessive curvature of the eye lens. The defect of myopia can be corrected

by wearing a concave lens of suitable power.

(ii) This part of the question is out of current syllabus

(iii) A bi-focal lens consists of both concave lens and convex lens. The upper portion of the lens

is concave lens and consequently lower portion is the convex lens. Generally people sufferingfrom the defect of presbyopia are prescribed to use bi-focal lens to correct the defect of vision.

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The upper portion of the lens i.e., concave part facilitates the distant vision whereas the lowerpart of the lens facilitates the nearby vision.

(iv) Far-sightedness is also known as hypermetropia. A person suffering from far-sightedness

cannot see nearby objects clearly, but can see distant objects clearly. This defect may be caused

because of either a decrease in size of the eyeball or the very high focal length of the eye lens.The defect of hypermetropia can be cured by using a convex lens of appropriate power.

(b)

OR

This part of the question is out of current syllabus


(a) What are 'magnetic field lines'? How is the direction of a magnetic field at a point

determined?(b) Draw two field lines around a bar magnet along its length on its two sides and mark the fielddirections on them by arrow marks.

(c) List any three properties of magnetic field lines.

Solution:

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(a) Magnetic field is the space around the magnet where its influence can be detected.

Magnetic field lines are closed continuous curves which depict the magnetic field of a

magnet. Outside of a magnet, they are directed from North Pole to South Pole of the

magnet.

The direction of magnetic field at a point is determined by placing a small magnetic

compass at that point. The direction towards which the North Pole of the compass needle

points is taken to be the direction of the magnetic field at that point.

(b)

(c) Three properties of magnetic field lines are:

(i) They always travel from North Pole to South Pole outside of a magnet.

(ii) They are closed continuous curves.

(iii) They never intersect each other.

Section B


Write the expanded form of the abbreviation AIDS.

Solution:

Acquired Immuno Deficiency Syndrome


Why is one arm in sub-metacentric chromosome longer than the other?

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Solution:



What is 'Green House Effect'?

Solution:

The increase in the average temperature of the earths surface due to the increase in

concentration of greenhouse gases such as carbon dioxide, methane, etc. is called greenhouseeffect.


What is 'eutrophication'? Write its two harmful effects.

Solution:



List any four practices which help in protecting our environment.

OR

Describe any four modes of disposal of waste.

Solution:

Four ways of protecting the environment are:

i. Afforestationii. Reducing the use of fossil fuels

iii. Proper management of the resourcesiv. Preventing air and water from getting polluted

OR

Four ways of waste disposal are:

i. Using separate bins for disposing biodegradable and non-biodegradable wastesii. Reduction in the use of non-biodegradable wastes

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iii. Composting of biodegradable wastesiv. Separation of materials that can be reused or recycled


What is 'translocation'? Why is it essential for plants? Where in plants are the followingsynthesized: (i) Sugars (it) Hormones

OR

What is 'clotting of blood'? Write a flow chart showing major events taking place in clotting of

blood.

Solution:

The transport of soluble products of photosynthesis is known as translocation. Translocation in

plants occurs by means of the vascular tissue known as phloem. Translocation is necessarybecause without it, the food prepared by the leaves cannot reach other parts of the plant.

i. In plants, the synthesis of sugars takes place in the leaves by the process ofphotosynthesis.

ii. Hormones are synthesised away from their target site.OR



Draw a diagram of human brain and label on it the following of its parts:

(i) Cerebrum (ii) Meninges

(iii) Medulla Oblongata (iv) Cerebellum

Solution:

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Differentiate between 'self pollination' and 'cross pollination'. Describe 'double fertilization' in

plants.

Solution:Self pollination Cross pollination

When the transfer of pollen grains takes place

from the stamen to the stigma of the sameflower, it is known as self pollination.

When the pollen grains are transferred from the

stamen of one flower to the stigma of anotherflower, it is known as cross pollination.

Double fertilisation



What is 'organic evolution'? How do embryological studies provide evidence for evolution?

Solution:



Explain the process of 'photosynthesis' in plants. List four factors which influence this process

and describe how each of them affects the rate of the photosynthesis process.

Solution:

Photosynthesis is the process by which plant cells prepare food (carbohydrates) from inorganic

raw materials such as carbon dioxide and water in presence of sunlight and chlorophyll.

The process of photosynthesis takes place in two phases:

Light reaction It requires light which is absorbed by chlorophyll molecules to split watermolecules into hydrogen and oxygen. ATP and NADPH2 are produced during this phase and it

occurs in the thylakoid membrane of the chloroplasts.

Dark reaction It does not require light energy and it occurs in the stroma of chloroplasts. Inthis phase, the ATP and NADPH2 formed during light reaction are utilised and CO2 is reduced toform carbohydrates.

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The four factors affecting the rate of photosynthesis are:

i. Sunlight Sunlight provides the energy required for the preparation of food by plants. Inthe absence of sunlight, photosynthesis cannot take place.

ii.

Carbon dioxide Carbon dioxide acts as the substrate for photosynthesis. During thisprocess, carbon dioxide and water are converted into carbohydrates.

iii. Water During photosynthesis, water is photolysed into oxygen and hydrogen and itprovides the energy for photosynthesis.

iv. Chlorophyll Chlorophyll is the green pigment present in the leaves which absorbssunlight.

v. ection Avi. Question 1 ( 0.5 marks)

vii. The correct procedure for preparing a colloidal solution of egg albumin in water is:viii. (1) to break the egg shell, take only the white portion and to add it to water with constant

stirring.ix. (2) to break the egg shell, take only the yellow portion and to add it to boiling water with

constant stirring.x. (3) to boil the egg first, to break the egg shell, to add the white portion to ice cold water

and to mix.

xi. (4) to boil the egg first, to break the egg shell, to add the yellow portion to water and tomix.

xii. Question 2 ( 0.5 marks)xiii. Four students (A), (B), (C) and (D) independently observed the evaporation of water

under different conditions, and recorded the temperature of water at regular intervals as

shown below.

Student Placing of experimental set up in/under Temperature recording for 15 minutes

(A) sun increased gradually

(B) open air decreased gradually

(C) a fan initially increased, then became constant

(D) a corner of the room initially increased, then gradually decreased

xiv. The correct recording of observations is that of the student:xv. (1) (A)

xvi. (2) (B)xvii. (3) (C)

xviii. (4) (D)xix. Question 3 ( 0.5 marks)

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xx. A student takes a mixture of sand and ammonium chloride in china dish and heats itunder a funnel fitted with a plug over a flame. He would observe that:

xxi. (1) solid sand gets deposited on the lower cooler parts of the funnel while solidammonium chloride remains in the china dish.

xxii. (2) sand and ammonium chloride get deposited on hotter parts of the funnel.xxiii.

(3) ammonium chloride gets deposited on the cooler parts of the funnel and sand remainsin the china dish.

xxiv. (4) sand collects on cooler parts of the funnel while ammonium chloride melts in thechina dish.

xxv. Question 4 ( 0.5 marks)xxvi. A student takes some water in a beaker and heats it over a flame for determining its

boiling point. He keeps on taking its temperature readings. He would observe that the

temperature of water:xxvii. (1) keeps on increasing regularly

xxviii. (2) keeps on increasing irregularlyxxix. (3) first increases slowly, then decreases rapidly and eventually becomes constantxxx.

(4) first increases gradually and then becomes constantxxxi. Question 5 ( 0.5 marks)

xxxii. While performing an experiment on verifying the laws of reflection of sound, a student isto choose between (i) a narrow or a wide tube and (ii) a strong or a faint source of sound.

xxxiii. The observed experimental difference, between the values of angle of incidence andangle of reflection, is likely to be minimum when he chooses a:

xxxiv. (1) narrow tube and a faint sourcexxxv. (2) wide tube and a faint source

xxxvi. (3) narrow tube and a strong sourcexxxvii. (4) wide tube and a strong source

xxxviii. Question 6 ( 0.5 marks)xxxix. The magnitude of zero error of the spring balance and least count of the measuring

cylinder, shown here, are, respectively:

xl.xli. (1) 2.5 g and 0.1 mL

xlii. (2) 5.0 g and 0.1 mL

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xliii. (3) 2.5 g and 0.2 mLxliv. (4) 5.0 g and 0.2 mLxlv. Question 7 ( 0.5 marks)

xlvi. For plotting temperature-time graph for a hot body, as it cools to room temperature, astudent is to choose one each from each of the following pairs.

xlvii.

A: Calorimeterxlviii. (i) blackened from outsidexlix. (ii) polished from outside

l. B: Base for keeping the calorimeterli. (i) insulated

lii. (ii) metallicliii. In order to get the correct graph he should prefer to choose:liv. (1) A (i), B (ii)lv. (2) A (ii), B (ii)

lvi. (3) A (i), B (i)lvii. (4) A (ii), B (i)

lviii.

Question 8 ( 0.5 marks)lix. A student sets up a slinky on a smooth table top in the manner shown here.

lx.lxi. How can he produce transverse waves in the slinky by moving its free end Q?

lxii. (1) at an angle of 45 with the table toplxiii. (2) backward and forward along the length of the slinkylxiv. (3) up and downlxv. (4) left and right

lxvi. Question 9 ( 0.5 marks)lxvii. A student carefully observes the parts labelled A and B in the given diagram and

classifies the plant correctly as:

lxviii.lxix. (1) a bryophytelxx. (2) a pteridophyte

lxxi. (3) a gymnospermlxxii. (4) an angiosperm

lxxiii. Question 10 ( 0.5 marks)

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lxxiv. Four students (A D), independently observed parenchyma under the microscope andlabelled the parts, marked I, II, III, IV, V, as per the record given below.

lxxv.Student I II III IV V

A Cell membrane Nucleus Cell wall Vacuole Cytoplasm

B Cytoplasm Cell membrane Vacuole Cell wall Nucleus

C Vacuole Cell wall NucleusCell

membrane

Cytoplasm

D Cell wall Inter cellular space Nucleus Cytoplasm Vacuole

lxxvi. The labelling has been done correctly by student:lxxvii. (1) A

lxxviii. (2) Blxxix. (3) Clxxx. (4) D

lxxxi. Question 11 ( 0.5 marks)lxxxii. A specimen of a fish was given to students to identify the externally visible chordate

feature in it. The students would look for:

lxxxiii. (1) Operculumlxxxiv. (2) Notochordlxxxv. (3) Dorsal tubular nerve cordlxxxvi. (4) Post anal tail

lxxxvii. Question 12 ( 0.5 marks)lxxxviii. A student adds a few drops of the universal indicator to a solution of dilute hydrochloric

acid in the way shown here. He would observe that the colour of the solution changesfrom colourless to:

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lxxxix.xc. (1) red

xci. (2) yellowxcii. (3) violet

xciii. (4) greenxciv. Question 13 ( 0.5 marks)xcv. A student takes some zinc granules in a test tube and adds dilute hydrochloric acid to it.

He would observe that the colour of the zinc granules changes to:xcvi. (1) white

xcvii. (2) blackxcviii. (3) brown

xcix. (4) yellowc. Question 14 ( 0.5 marks)

ci. The set up, used in the laboratory, to collect sulphur dioxide, is that shown in figure:

cii.ciii. (1) Iciv. (2) IIcv. (3) III

cvi. (4) IVcvii. Question 15 ( 0.5 marks)

cviii. A student determines the focal length of a device X, by focussing the image of a far offobject on the screen positioned as shown in the figure below.

cix.cx. The device X is a:

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cxi. (1) Convex lenscxii. (2) Concave lens

cxiii. (3) Convex mirrorcxiv. (4) Concave mirrorcxv. Question 16 ( 0.5 marks)

cxvi.

A student traces the path of a ray of light passing through a rectangular glass slab.

cxvii.cxviii. For measuring the angle of incidence, he must position the protractor in the manner

shown in figure:

cxix. (1) Acxx. (2) B

cxxi. (3) Ccxxii. (4) D

cxxiii. Question 17 ( 0.5 marks)cxxiv. In an experiment on finding the equivalent resistance of two resistors, connected in

series, a student connects the terminals of the voltmeter, to:cxxv. (1) one terminal of each of the two resistors and these terminals are not interconnected.

cxxvi. (2) one terminal of each of the two resistors and these terminals are also interconnected.cxxvii. (3) both the terminals of each of the two resistors.

cxxviii. (4) both the terminals of one resistor and one terminal of the other resistor.cxxix. Question 18 ( 0.5 marks)cxxx. In the experiment to show that CO2 is given out during respiration, the student uses:

cxxxi. (1) Lime watercxxxii. (2) Alcohol

cxxxiii. (3) KOH solutioncxxxiv. (4) Iodine solutioncxxxv. Question 19 ( 0.5 marks)

cxxxvi. Raisins are soaked in water for determining the percentage of water absorbed by raisins.The formula, used by a student, for calculating the percentage of water absorbed, is:

cxxxvii. (1)cxxxviii. (2)

cxxxix. (3)cxl. (4)

cxli. Question 20 ( 0.5 marks)

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clxii.clxiii. The arrangement, that would give correct results, is that of student:clxiv. (1) (A)clxv. (2) (B)

clxvi. (3) (C)clxvii. (4) (D)

clxviii. Question 23 ( 1.0 marks)clxix. Which one of the following is the correct step, in the procedure for making a temporary

slide of human cheek cells?

clxx. (1) Place the cheek cell scrapings in a watch glass containing water.clxxi. (2) Place cheek cell scrapings in the centre of a clean slide.clxxii. (3) Dip the toothpick, containing cheek cell scrapings, in the stain and then transfer to a

clean slide.

clxxiii. (4) Obtain cheek cells, directly on the slide, using its edge to scrape the inside of thecheek.

clxxiv. Question 24 ( 1.0 marks)clxxv. While observing the occurrence of plasmolysis in onion peel cells, four students (WZ)

respectively placed the peels in four different liquids (AD): (A): Water, (B): Sugarsolution, (C): Alcohol and (D): Safranin

clxxvi. The correct choice of liquid is that of student:clxxvii. (1) W

clxxviii.

(2) Xclxxix. (3) Yclxxx. (4) Z

clxxxi. Question 25 ( 1.0 marks)clxxxii. A student takes Cu, Al, Fe and Zn strips, separately in four test tubes labelled as I, II, III

and IV respectively. He adds 10 mL of freshly prepared ferrous sulphate solution to each

test tube and observes the colour of the metal residue in each case.

clxxxiii.clxxxiv. He would observe a black residue in the test tubes:clxxxv. (1) (I) and (II)

clxxxvi. (2) (I) and (III)clxxxvii. (3) (II) and (III)

clxxxviii. (4) (II) and (IV)clxxxix. Question 26 ( 1.0 marks)

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cxc. Four students observed the colour and odour of acetic acid and its reaction with sodiumhydrogen carbonate. They tabulated their observations as given below.

Student Colour of acetic acid Odour of acetic acid Action with sodium hydrogen carbonate

A

B

C

D

blue

colourless

light green

light brown

fruity

smell of vinegar

odourless

rotten egg

gas evolves without bubbles

effervescence

gas evolves without bubbles

effervescence

cxci. The correct set of observation is that of student:cxcii. (1) A

cxciii. (2) Bcxciv. (3) Ccxcv. (4) D

cxcvi. Question 27 ( 1.0 marks)cxcvii. The following precautions were listed by a student in the experiment on study of

Dependence of current on potential difference.cxcviii. (A) Use copper wires as thin as possible for making connections.

cxcix. (B) All the connections should be kept tight.cc. (C) The positive and negative terminals of the voltmeter and the ammeter should be

correctly connected.cci. (D) The zero error in the ammeter and the voltmeter should be noted and taken into

consideration while recording the measurements.ccii. (E) The key in the circuit, once plugged in, should not be taken out till all the

observations have been completed.cciii. The precautions that need to be corrected and revised are:cciv. (1) (A), (C) and (E)ccv. (2) (C) and (E)

ccvi. (3) (B) and (E)ccvii. (4) (A) and (E)

ccviii. Question 28 ( 1.0 marks)ccix. For three circuits, shown here

ccx.ccxi. the same two resistors R1 and R2 have been connected in parallel in all the circuits but the

voltmeter and the ammeter have been connected in three different positions. The relationbetween the three voltmeter and ammeter reading would be:

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ccxii. (1) V1 = V2 = V3 and I1 = I2 = I3ccxiii. (2) V1 V2 V3 and I1 = I2 = I3ccxiv. (3) V1 = V2 = V3 and I1 I2 I3ccxv. (4) V1 V2 V3 and I1 I2 I3

ccxvi. Question 29 ( 1.0 marks)ccxvii.

Four stages of binary fission in amoeba are shown below. The stage at which nuclearfission and cytokineses are observed is, stage

ccxviii.ccxix. (1) Iccxx. (2) II

ccxxi. (3) IIIccxxii. (4) IV

ccxxiii. Question 30 ( 1.0 marks)ccxxiv. Four students, A, B, C and D, make the records given below, for the parts marked X and

Y in this diagram.

ccxxv.Student X Y

A

B

C

D

Stoma

Guard cell

Epidermal cell

Stoma

Guard cell

Stoma

Stoma

Epidermal cell

ccxxvi. The correct record, out of these, is that of student:ccxxvii. (1) A

ccxxviii. (2) Bccxxix. (3) Cccxxx. (4) D


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Subjective Testccxxxii. (i) The question paper comprises of two sections, A and B. You are to attempt both

the sections.ccxxxiii.ccxxxiv. (ii) All questions are compulsory.ccxxxv.

ccxxxvi. (iii) There is no overall choice. However, internal choice has been provided in all the

three questions of five marks category. Only one option in such questions is to be

attempted.ccxxxvii.

ccxxxviii. (iv) All questions of Section A and all questions of Section B are to be attemptedseparately.

ccxxxix.ccxl. (v) Questions number1to 6 in Section A and 17to 19in Section B are short answer

type questions. These questions carry one mark each.ccxli.

ccxlii.

(vi) Questions number7to 10in Section A and 20to 24 in Section B are short answertype questions and carry two marks each.

ccxliii.ccxliv. (vii) Questions number11to 14 in Section A and 25 and 26 in Section B are also short

answer type questions and carry three marks each.ccxlv.

ccxlvi. (viii) Questions number15 and 16 in section A and question number27in section Bare long answer type questions and carry five marks each.

ccxlvii. Section Accxlviii. Question 1 ( 1.0 marks)

ccxlix. Name the part of our eyes that helps us to focus near and distant objects in quicksuccession.

ccl. Question 2 ( 1.0 marks)ccli. The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a

mirror. What will be the focal length of this mirror? Which type of spherical mirror will itprovide?

cclii. Question 3 ( 1.0 marks)ccliii. What is nature of the image formed by a concave mirror if the magnification produced by

the mirror is + 4?ccliv. Question 4 ( 1.0 marks)cclv. A charged particle enters at right angles into a uniform magnetic field as shown. What

should be the nature of charge on the particle if it begins to move in a direction pointing

vertically out of the page due to its interaction with the magnetic field?

cclvi.cclvii. Question 5 ( 1.0 marks)

cclviii. On what basis is a chemical equation balanced?

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cclix. Question 6 ( 1.0 marks)cclx. State two characteristic features of carbon which when put together give rise to a large

number of carbon compounds.cclxi. Question 7 ( 2.0 marks)

cclxii. Write any two observations in an activity which may suggest that a chemical reaction hastaken place. Give an example in support of your answer.cclxiii. Question 8 ( 2.0 marks)

cclxiv. What are fossil fuels? Write two disadvantages of burning fossil fuels.cclxv. Question 9 ( 2.0 marks)

cclxvi. Two coils A and B of insulated wires are kept close to each other. Coil A is connected toa galvanometer while coil B is connected to a battery through a key. What would happenif

cclxvii. (i) a current is passed through coil B by plugging the key, andcclxviii. (ii) the current is stopped by removing the plug from the key?

cclxix. Explain your answer mentioning the name of the phenomena involved.cclxx. Question 10 ( 2.0 marks)

cclxxi.

What is a solenoid? Draw the pattern of magnetic field lines of a solenoid through whicha steady current flows. What does the pattern of field lines inside the solenoid indicate?

cclxxii. Question 11 ( 2.0 marks)cclxxiii. What is Hypermetropia (far sightedness)? Draw a ray diagram to show how this defect

can be corrected using a lens.cclxxiv. Question 12 ( 2.0 marks)cclxxv. Mention any four limitations in harnessing wind energy on a large scale.

cclxxvi. Question 13 ( 3.0 marks)cclxxvii. At what distance should an object be placed from a lens of focal length 25 cm to obtain

its image on a screen placed on the other side at a distance of 50 cm from the lens? What

will be the magnification produced in this case?cclxxviii. Question 14 ( 3.0 marks)

cclxxix. Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronicshells but different number of electrons in their outermost shell. It was found that

elements A and G combine to form an ionic compound. This compound is added in asmall amount to almost all vegetable dishes during cooking. Oxides of elements A and B

are basic in nature while those of E and F are acidic. The oxide of D is almost neutral.Based on the above information answer the following questions:

cclxxx. (i) To which group or period of the periodic table do the listed elements belong?cclxxxi. (ii) What would be the nature of compound formed by a combination of elements B and

F?cclxxxii. (iii) Which two of these elements could definitely be metals?

cclxxxiii. (iv) Which one of the eight elements is most likely to be found in gaseous state at roomtemperature?

cclxxxiv. (v) If the number of electrons in the outermost shell of elements C and G be 3 and 7respectively, write the formula of the compound formed by the combination of C and G.

cclxxxv. Question 15 ( 3.0 marks)cclxxxvi. No chemical reaction takes place when granules of a solid, A, are mixed with the powder

of another solid, B. However when the mixture is heated, a reaction takes place betweenits components. One of the products, C, is a metal and settles down in the molten state

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while the other product, D, floats over it. It was observed that the reaction is highlyexothermic.

cclxxxvii. (i) Based on the given information make an assumption about A and B and write achemical equation for the chemical reaction indicating the conditions of reaction,

physical state of reactants and products and thermal status of reaction.

cclxxxviii.

(ii) Mention any two types of reactions under which above chemical reaction can beclassified.cclxxxix. Question 16 ( 3.0 marks)

ccxc. Name the functional group of organic compounds that can be hydrogenated. With thehelp of suitable example explain the process of hydrogenation mentioning the conditions

of the reaction and any one change in physical property with the formation of the product.Name any one natural source of organic compounds that are hydrogenated.

ccxci. Question 17 ( 5.0 marks)ccxcii. Derive the expression for the heat produced due to a current I flowing for a time

interval t through a resistor R having a potential difference V across its ends. Withwhich name is the relation known? How much heat will an instrument of 12W produce in

one minute if it is connected to a battery of 12V?ccxciii. ORccxciv. Explain with the help of a labelled circuit diagram how you will find the resistance of a

combination of three resistors, or resistanceR1, R2 and R3, joined in parallel. Also

mention how you will connect the ammeter and the voltmeter in the circuit whenmeasuring the current in the circuit and the potential difference across one of the three

resistors of the combination.ccxcv. Question 18 ( 5.0 marks)

ccxcvi. Write the names and symbols of two most reactive metals belonging to group 1 of theperiodic table. Explain by drawing electronic structure how either one of the two metals

reacts with a halogen. With which name is the bond formed between these elementsknown and what is the class of the compound so formed known? State any four physical

properties of such compounds.

ccxcvii. ORccxcviii. What is meant by refining of metals? Name the most widely used method of refining

impure metals produced by various reduction processes. Describe with the help of a

labelled diagram how this method may be used for refining of copper.

ccxcix. Section Bccc. Question 19 ( 1.0 marks)

ccci. Name the hormone that helps in regulating level of sugar in our blood. Name the glandthat secrets it.

cccii. Question 20 ( 1.0 marks)ccciii. A person lives near a forest. Make a list of four items which he can get from the forest tomeet his daily needs.ccciv. Question 21 ( 1.0 marks)cccv. Name the green dot like structures in some cells observed by a student when a leaf peel

was viewed under a microscope. What is this green colour due to?cccvi. Question 22 ( 2.0 marks)

cccvii. What is phototropism? Describe an activity to demonstrate phototropism.cccviii. Question 23 ( 2.0 marks)

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cccix. List any two differences between pollination and fertilisation.cccx. Question 24 ( 2.0 marks)

cccxi. Give one example each of characters that are inherited and the ones that are acquired inhumans. Mention the difference between the inherited and the acquired characters.

cccxii. Question 25 ( 3.0 marks)cccxiii.

How is ozone formed in the higher level of atmosphere? Damage to the ozone layer is acause of concern. Justify this statement.

cccxiv. Question 26 ( 3.0 marks)cccxv. Write the full form of DNA. Name the part of the cell where it is located? Explain its role

in the process of reproduction of the cell.

cccxvi. Question 27 ( 5.0 marks)cccxvii. Explain the process of digestion of food in mouth, stomach and small intestine in human

body.

cccxviii. ORcccxix. (a) List the three events that occur during the process of photosynthesis. Explain the role

of stomata in this process.

cccxx.

(b) Describe an experiment to show that sunlight is essential for photosynthesis.


Subjective Test

(i) The question paper comprises of two sections, A and B. You are to attempt both thesections.


(iii) There is no overall choice. However, internal choice has been provided in all the three

questions of five marks category. Only one option in such questions is to be attempted.

(iv) All questions of Section A and all questions of Section B are to be attempted separately.

(v) Questions number1to 6 in Section A and 17to 19in Section B are short answer typequestions. These questions carry one mark each.

(vi) Questions number7to 10in Section A and 20to 24 in Section B are short answer type

questions and carry two marks each.

(vii) Questions number11to 14 in Section A and 25 and 26 in Section B are also shortanswer type questions and carry three marks each.

(viii) Questions number15 and 16 in section A and question number27in section B are long

answer type questions and carry five marks each.

Section A


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Name the part of our eyes that helps us to focus near and distant objects in quick succession.

Solution:

The part of our eyes that helps us to focus near and distant objects in quick succession is eye

lens.


The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror.

What will be the focal length of this mirror? Which type of spherical mirror will it provide?

Solution:

The focal length of the mirror will be

The outer surface of a hollow sphere of aluminium will act as a convex mirror.


What is nature of the image formed by a concave mirror if the magnification produced by the

mirror is + 4?

Solution:

The nature of the image formed by a concave mirror if its magnification is +4, will be virtual,

erect and larger than the object.


A charged particle enters at right angles into a uniform magnetic field as shown. What should bethe nature of charge on the particle if it begins to move in a direction pointing vertically out of

the page due to its interaction with the magnetic field?

Solution:

The nature of charge on the particle should be positive.

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On what basis is a chemical equation balanced?

Solution:

Law of conservation of mass forms the basis of balancing chemical equations. In a balanced

chemical equation, the number of atoms of each element is equal on both sides of the equation.


State two characteristic features of carbon which when put together give rise to a large number of

carbon compounds.

Solution:

The two characteristic features of carbon which when put together give rise to large number ofcarbon compounds are

1. The ability to catenate2. Tetravalency of carbon atom


Write any two observations in an activity which may suggest that a chemical reaction has taken

place. Give an example in support of your answer.

Solution:

A chemical change can be confirmed by any of the following observations:

y Change in temperaturey Evolution of gas

For example: Calcium oxide reacts vigorously with water to produce calcium hydroxide. Duringthis process, a large amount of heat is also evolved, which increases the temperature of the

system. This confirms that a chemical reaction has taken place.

Also, when calcium carbonate is heated, it decomposes to form calcium oxide and carbondioxide.

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In this reaction, calcium carbonate breaks down to form calcium oxide and carbon dioxide. Here,evolution of the gas (carbon dioxide) confirms that a chemical reaction has taken place.


What are fossil fuels? Write two disadvantages of burning fossil fuels.

Solution:

Fossil fuels are those fuels that were formed by remains of dead animals and plants that got

buried deep inside the earth millions of years ago. Fossil fuels mainly contain hydrocarbons.

Coal, petroleum and natural gas are fossil fuels.

Disadvantages of burning fossil fuels:

1. The burning of fossil fuels produces large amounts of acidic gases such as sulphurdioxide and nitrogen dioxide. These acidic gases combine with rainwater to form acidssuch as sulphuric acid and nitric acid. Acid rains have been observed in many parts of the

world after the industrial revolution in Europe.2. Fossil fuels such as coal leave a lot of ash content after burning. This ash is mostly

thrown into rivers, leading to their pollution. Such contaminated water causes serioushealth problems.

3. The burning of fossil fuels produces smoke, leading to air pollution.4. The burning of fossil fuels releases carbon dioxide a greenhouse gas which is the main

cause for global warming.5. Fossil fuels have a limited supply on the earth. They cannot be replenished at the same

rate at which they are used.

(Any two points will serve the purpose)


Two coils A and B of insulated wires are kept close to each other. Coil A is connected to a

galvanometer while coil B is connected to a battery through a key. What would happen if

(i) a current is passed through coil B by plugging the key, and

(ii) the current is stopped by removing the plug from the key?

Explain your answer mentioning the name of the phenomena involved.

Solution:

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(i) When current is made to pass through coil B, by plugging the key in, for that instant, thegalvanometer connected to coil A shows a deflection, i.e., current passes through coil A as well.

(ii) When current is stopped through coil B by taking the plug of the key out, for that instant, the

galvanometer connected to coil A again shows a deflection, this time, however, in the opposite

direction. That is, a current passes through coil A in the opposite direction.

The observations are made because whenever we change the current in the coil B, the magnetic

field associated with it and the coil A in its proximity changes. At the very instant of pluggingthe key in or taking the plug out, there is an instantaneous flow of current and a change in the

magnetic field associated with the coil B. During this instantaneous moment, the current in coilB reaches from zero to the maximum or from the maximum to zero. This changing magnetic

field of coil B induces a current in the coil A.

The phenomenon is known as electromagnetic induction.


What is a solenoid? Draw the pattern of magnetic field lines of a solenoid through which a

steady current flows. What does the pattern of field lines inside the solenoid indicate?

Solution:

A solenoid is a coil of several circular turns of insulated conducting wire, wrapped closely in the

shape of a cylinder.

Pattern of magnetic field lines of a solenoid through which a steady current flows:

The pattern of magnetic field lines inside a current-carrying solenoid indicates that the magneticfield is uniform, i.e., strength of the magnetic field is the same, everywhere inside the solenoid.


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What is Hypermetropia (far sightedness)? Draw a ray diagram to show how this defect can becorrected using a lens.

Solution:

Hypermetropiais a defect of vision in which a person cannot see nearby objects clearly, but hasno problems in seeing distant objects.

Corrected vision for a hypermetropic eye by using a convex lens:


Mention any four limitations in harnessing wind energy on a large scale.

Solution:

Four limitations in harnessing wind energy on a large scale are as follows:

i) Wind mills or wind energy plants can only be built in places where wind blows at a high speed

for the greater part of a year.

ii) For a large-scale windmill to be productive, the wind speed must be atleast 15 km/h.

iii) A large-scale windmill establishment requires large area of land.

iv) The initial cost of establishment of the farm is quite high.


At what distance should an object be placed from a lens of focal length 25 cm to obtain its imageon a screen placed on the other side at a distance of 50 cm from the lens? What will be the

magnification produced in this case?

Solution:

Given that,

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Focal length,f= 25 cm

Image distance, v = 50 cm

Form the lens formula,

Or, u = 50 cm

Magnification,

The object must be placed 50 cm away from the lens, on the other side to produce amagnification of 1.


Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells but

different number of electrons in their outermost shell. It was found that elements A and G

combine to form an ionic compound. This compound is added in a small amount to almost allvegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of

E and F are acidic. The oxide of D is almost neutral. Based on the above information answer thefollowing questions:

(i) To which group or period of the periodic table do the listed elements belong?

(ii) What would be the nature of compound formed by a combination of elements B and F?

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(iii) Which two of these elements could definitely be metals?

(iv) Which one of the eight elements is most likely to be found in gaseous state at roomtemperature?

(v) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively,write the formula of the compound formed by the combination of C and G.

Solution:

(i) The elements A, B, C, D, E, F, G and H belong to the third period of the periodic table and to

the following groups.

A belongs to group 1

B belongs to group 2

C belongs to group 3

D belongs to group 14

E belongs to group 15

F belongs to group 16

G belongs to group 17

H belongs to group 18

(ii) The compounds formed by B and F would be ionic in nature.

(iii) Elements A and B are definitely metals.

(iv) Element H is most likely to found in gaseous state at room temperature.

(v) The formula of the compound will be CG3.


No chemical reaction takes place when granules of a solid, A, are mixed with the powder of

another solid, B. However when the mixture is heated, a reaction takes place between itscomponents. One of the products, C, is a metal and settles down in the molten state while the

other product, D, floats over it. It was observed that the reaction is highly exothermic.

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(i) Based on the given information make an assumption about A and B and write a chemicalequation for the chemical reaction indicating the conditions of reaction, physical state of

reactants and products and thermal status of reaction.

(ii) Mention any two types of reactions under which above chemical reaction can be classified.

Solution:

(i) Solid A is assumed to be MnO2 and solid B to be Aluminium (Al).

When the mixture of MnO2 andAl is heated, manganese (Mn) is produced in molten state and

aluminium oxide (Al2O3) floats over it. Mn is produced in the molten state as a lot of heat energyis released in the process.

The chemical equation for the reaction can be written as:

(ii) The types of reaction under which the above reaction is classified are

1. Redox reaction2. Displacement reaction


Name the functional group of organic compounds that can be hydrogenated. With the help of

suitable example explain the process of hydrogenation mentioning the conditions of the reaction

and any one change in physical property with the formation of the product. Name any onenatural source of organic compounds that are hydrogenated.

Solution:

The functional group of organic compounds that can be hydrogenated are alkenes andalkynes

Hydrogen can be added to unsaturated hydrocarbons in the presence of nickel to yield saturated

hydrocarbons. In this reaction, nickel acts as a catalyst.

Onhydrogenation, the unsaturated fatty acids which are liquid at room temperature become

saturated and change to solid.

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A natural source of organic compound that is hydrogenated is vegetable oil.


Derive the expression for the heat produced due to a current I flowing for a time interval t

through a resistor R having a potential difference V across its ends. With which name is therelation known? How much heat will an instrument of 12W produce in one minute if it isconnected to a battery of 12V?

OR

Explain with the help of a labelled circuit diagram how you will find the resistance of acombination of three resistors, or resistanceR1, R2 and R3, joined in parallel. Also mention how

you will connect the ammeter and the voltmeter in the circuit when measuring the current in thecircuit and the potential difference across one of the three resistors of the combination.

Solution:

Consider a resistor of resistance R. Let the current flowing through this resistor be Iand thepotential difference across it be V.

In time t, let Q amount of charge flows through the resistor.

Work done on moving this charge, W= VQ ... (1)

According to the definition of electric current,

Q = I t

Putting this in equation (1),

W= V I t

This work done is dissipated as heat.

Hence,

Heat produced,H= W= VIt

H= VIt... (2)

According to Ohms law, V= IR.

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Putting this in equation (2),

H= IR It

This relation is known as Joules law of heating.

Power, P= 12 W

Potential difference, V=12 V

Time duration of current flow, t= 1 min = 60 s

H= P t

= 12 W 60 s

= 720 J

The heat generated by the instrument of 12 W in a minute is 720 J.

OR

The given figure shows a circuit consisting of three resistorsR1, R2 and R3 connected in parallel.

The total current in the circuit (I) gets divided among the three resistors asI1, I2 and I3.

Thus,

I= I1 + I2 + I3

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Applying Ohms law to each resistor,

Let the equivalent resistance of the circuit beReq.

Applying Ohms law to the equivalent circuit,

Using these,

An ammeter has to be connected in series with the combination of all three resistors so that thecurrent passes through the ammeter becomes equal to the total current through the circuit.

The voltmeter has to be connected in parallel to that resistor across which the potential differencehas to be measured.


Write the names and symbols of two most reactive metals belonging to group 1 of the periodictable. Explain by drawing electronic structure how either one of the two metals reacts with a

halogen. With which name is the bond formed between these elements known and what is the

class of the compound so formed known? State any four physical properties of such compounds.

OR

What is meant by refining of metals? Name the most widely used method of refining impure

metals produced by various reduction processes. Describe with the help of a labelled diagramhow this method may be used for refining of copper.

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Solution:

Two most reactive elements of group 1 of the periodic table are sodium (Na) and potassium (K)

As the ions of sodium and chlorine are oppositely charged, they attract each other bystrong electrostatic forces. The reaction between sodium and chlorine can be represented

as follows:

The bond formed between these elements is known as ionic orelectrostatic bond.

Sodium chloride belongs to the class ionic compounds.

Following are the four physical properties of ionic compounds.

1. Ionic compounds exist in solid state2. Ionic compounds have high melting and boiling points3. Ionic compounds are soluble in polar solvents such as water and insoluble in non-polar or

organic solvents (kerosene and petrol).

4. Ionic compounds conduct electricity in their molten or aqueous state.OR

Refining is the process of obtaining pure metal from its impure sample.

Electrolytic refining is the most widely used method of refining impure metals produced byvarious reduction processes.

Electrolytic refining of copper

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In this process, anode is made of a large block of impure metal and cathode is made of a

thin strip of pure metal. The electrolyte used in the process is acidified copper sulphatesolution.

When electric current is passed through the electrolyte, the positively charged metal ionspresent in the electrolyte get attracted towards the negatively charged cathode. When

metal ions reach near the cathode, they gain electrons from it and get deposited there.Hence, as the time increases, the cathode becomes thicker and thicker.

As the metal ions from the electrolyte move towards the cathode, an equal amount of ions

are released by the anode into the solution. Therefore, as the time increases, the size ofthe block of impure metal keeps on decreasing i.e. anode becomes thinner and thinner.

The soluble impurities present in the impure metal block go into the electrolytic solution. And

the insoluble impurities settle down at the bottom of the container below the anode and areknown as anode mud.

Section B


Name the hormone that helps in regulating level of sugar in our blood. Name the gland that

secrets it.

Solution:

Insulin helps in regulating sugar level in our blood. This hormone is secreted by pancreas gland.


A person lives near a forest. Make a list of four items which he can get from the forest to meet

his daily needs.

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Solution:

Four products that a person will get from the forest are timber, firewood, honey and animal

meat.


Name the green dot like structures in some cells observed by a student when a leaf peel wasviewed under a microscope. What is this green colour due to?

Solution:

The green dot-like structures in some cells observed by the student when a leaf peel was viewed

under a microscope are chloroplasts. The green colour is due to the presence of green pigmentchlorophyll.


What is phototropism? Describe an activity to demonstrate phototropism.

Solution:

The growth movement in plants in response to light stimulus is known as phototropism.

To demonstrate phototropism in plants a sunflower plant is taken and kept in sunlight. It will be

observed that the flower head of sunflower will move from east to west along with the movementof Sun. This shows that the flower head of sunflower is positively phototropic and moves in

response to sunlight stimulus.


List any two differences between pollination and fertilisation.

Solution:

Pollination Fertilization

Pollination is the transfer of pollen grains

carrying male gametes from the anther to pistil

of a flower. Pollination is of two typesselfpollination and cross pollination.

Fertilization is the fusion of male and female

gamete to form a zygote. It is also of two

typesinternal fertilization and externalfertilization.

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Pollination occurs with the help of certain

agents such as wind, water or animals

Fertilization occurs after pollination when the

pollen grain resides on stigma and forms apollen tube to transfer the male gamete into the

embryo sac in the ovary.


Give one example each of characters that are inherited and the ones that are acquired in humans.

Mention the difference between the inherited and the acquired characters.

Solution:

Eye colour or hair colour of a person is an example of inherited character whereas body weight is

an example of acquired character.

The basic difference between inherited and acquired character is that inherited character is

passed on from parent to offspring. On the other hand, acquired characters are acquired by anindividual during his lifetime depending upon his lifestyle.


How is ozone formed in the higher level of atmosphere? Damage to the ozone layer is a cause

of concern. Justify this statement.

Solution:

The ozone layer is continuously formed in the atmosphere because of the action of UV rays on

molecular oxygen. The high-energy UV radiations break down O2 molecules present in upperlayers of the atmosphere into nascent oxygen.

Then, this free oxygen atom combines with an oxygen molecule to form ozone.

Damage to the ozone is a cause of concern; this is because ozone depletion has created an holein the ozone layer over the Arctic region.

Damage in the ozone layer allows the harmful UV rays to reach the earth surface. UV rays can

cause

y skin cancer, ageing and corneal cataracts in human beings.

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y death of many phytoplankton leading to the increase in the rate of global warming.Increase in the global warming rate, in turn, leads to the melting of Arctic ice cap. This

may further result in the increase in the sea level.

Thus, it is justified to say that damage to the ozone is a cause of concern.


Write the full form of DNA. Name the part of the cell where it is located? Explain its role in the

process of reproduction of the cell.

Solution:

The full form of DNA is Deoxyribonucleic acid.

It is the genetic material found in the chromosomes, which are present in the nucleus of a cell.

It is a chemical that carries genetic information required by the cells to divide and produce

proteins.

DNA plays an important role in the reproduction of a cell. The reproducing cell producesan identical copy of DNA through some cellular mechanism. Since the newly formed copy of

DNA lacks an organised cellular structure, the cell gets divided to provide cell cover to thenewly formed DNA. Thus, two daughter cells are formed from the single cell as a result of the

copying of DNA.


Explain the process of digestion of food in mouth, stomach and small intestine in human body.

OR

(a) List the three events that occur during the process of photosynthesis. Explain the role ofstomata in this process.

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(b) Describe an experiment to show that sunlight is essential for photosynthesis.

Solution:

The process of digestion of food in mouth, stomach and small intestine is described as follows:

MouthDigestion of food begins in the mouth. Saliva present in mouth contains a digestive

enzyme, called salivary amylase, which breaks down starch into sugar.

StomachStomach stores and mixes the food received from the oesophagus with gastric juices.The main components of gastric juice are hydrochloric acid, mucus and pepsinogen.

Hydrochloric acid dissolves bits of food and creates an acidic medium. In this medium,

pepsinogen is converted to pepsin, which is a protein-digesting enzyme. Mucus protects the innerlining of the stomach from the action of HCl.

Small intestine

Small intestine is the site for complete digestion of carbohydrates, proteins andfats.

Small intestine produces intestinal juice from the glands present in its wall. The intestinal juice

helps in further digestion of food. Small intestine also obtains digestive juices from liver andpancreasthat helps in mixing of food.

The liverproduces bile juice that causes emulsification of fats and the pancreas produces

pancreatic juice for digesting proteins and emulsified fats.

This digested food is finally absorbed through the intestinal walls.

OR

a. The events that occur in plants during photosynthesis are

y Absorption of sunlight by the green pigment chlorophylly Conversion of light energy into chemical energy and the splitting of water molecule into

oxygen and hydrogeny Reduction of carbon dioxide into glucose

Role of stomata

Stomata are tiny pores present mainly on the surfaces of leaves. They are also present on the

surface of young stems and roots. Stomata are mainly engaged in the exchange of gases (entry ofCO2 and release of O2) associated with photosynthesis.

b. Sunlight is essential for photosynthesis

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Place a healthy, green, potted plant in a dark room for 12 days. This is done to ensure that theplant consumes all its reserve food and the leaves do not contain any starch. Then, cover a

portion on both sides of a green leaf with two uniform pieces of black paper. Fix the cover inposition with two paper clips.

Now, expose this plant to bright light. After a few hours, remove the leaf and decolourise it withalcohol. Now, test the presence of food (starch) by putting iodine solution on the leaf.

It can be observed that the covered portion of the leaf does not show any presence of starch

(food).

This is because plants store the food prepared by through the process of photosynthesis as starch.Starch reacts with iodine solution to give blueblack colour.

In the performed experiment, only those portions of the leaf that were exposed to sunlight couldphotosynthesise. Hence, the uncovered portion of the leaf gives blueblack colour when tested

with iodine.

The covered portion of the leaf did not receive any sunlight. Hence, starch was not produced inthis portion. So, it does not change its colour when treated with iodine solution.

Thus, it can be concluded that the sunlight is essential for photosynthesis.


Subjective Test(i) The question paper comprises of two sections, A and B. You are to attempt both thesections.


(iii) There is no overall choice. However, internal choice has been provided in all the three

questions of five marks category. Only one option in such questions is to be attempted.

(iv) All questions of Section A and all questions of Section B are to be attempted separately.

(v) Questions number1to 6 in Section A and 17to 19in Section B are short answer typequestions. These questions carry one mark each.

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(vi) Questions number7to 10in Section A and 20to 24 in Section B are short answer typequestions and carry two marks each.

(vii) Questions number11to 14 in Section A and 25 and 26 in Section B are also short

answer type questions and carry three marks each.

(viii) Questions number15 and 16 in section A and question number27in section B are longanswer type questions and carry five marks each.

Section A


Name the part of our eyes that helps us to focus near and distant objects in quick succession.

Solution:

The part of our eyes that helps us to focus near and distant objects in quick succession is eye

lens.


The outer surface of a hollow sphere of aluminium of radius 50 cm is to be used as a mirror.

What will be the focal length of this mirror? Which type of spherical mirror will it provide?

Solution:

The focal length of the mirror will be

The outer surface of a hollow sphere of aluminium will act as a convex mirror.


What is nature of the image formed by a concave mirror if the magnification produced by the

mirror is + 4?

Solution:

The nature of the image formed by a concave mirror if its magnification is +4, will be virtual,

erect and larger than the object.


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A charged particle enters at right angles into a uniform magnetic field as shown. What should bethe nature of charge on the particle if it begins to move in a direction pointing vertically out of

the page due to its interaction with the magnetic field?

Solution:

The nature of charge on the particle should be positive.


On what basis is a chemical equation balanced?

Solution:

Law of conservation of mass forms the basis of balancing chemical equations. In a balanced

chemical equation, the number of atoms of each element is equal on both sides of the equation.


State two characteristic features of carbon which when put together give rise to a large number of

carbon compounds.

Solution:

The two characteristic features of carbon which when put together give rise to large number of

carbon compounds are

1. The ability to catenate2. Tetravalency of carbon atom


Write any two observations in an activity which may suggest that a chemical reaction has takenplace. Give an example in support of your answer.

Solution:

A chemical change can be confirmed by any of the following observations:

y Change in temperature

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y Evolution of gasFor example: Calcium oxide reacts vigorously with water to produce calcium hydroxide. Duringthis process, a large amount of heat is also evolved, which increases the temperature of the

system. This confirms that a chemical reaction has taken place.

Also, when calcium carbonate is heated, it decomposes to form calcium oxide and carbondioxide.

In this reaction, calcium carbonate breaks down to form calcium oxide and carbon dioxide. Here,evolution of the gas (carbon dioxide) confirms that a chemical reaction has taken place.


What are fossil fuels? Write two disadvantages of burning fossil fuels.

Solution:

Fossil fuels are those fuels that were formed by remains of dead animals and plants that got

buried deep inside the earth millions of years ago. Fossil fuels mainly contain hydrocarbons.

Coal, petroleum and natural gas are fossil fuels.

Disadvantages of burning fossil fuels:

1. The burning of fossil fuels produces large amounts of acidic gases such as sulphurdioxide and nitrogen dioxide. These acidic gases combine with rainwater to form acidssuch as sulphuric acid and nitric acid. Acid rains have been observed in many parts of the

world after the industrial revolution in Europe.2. Fossil fuels such as coal leave a lot of ash content after burning. This ash is mostly

thrown into rivers, leading to their pollution. Such contaminated water causes serioushealth problems.

3. The burning of fossil fuels produces smoke, leading to air pollution.4. The burning of fossil fuels releases carbon dioxide a greenhouse gas which is the maincause for global warming.

5. Fossil fuels have a limited supply on the earth. They cannot be replenished at the samerate at which they are used.

(Any two points will serve the purpose)

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Two coils A and B of insulated wires are kept close to each other. Coil A is connected to a

galvanometer while coil B is connected to a battery through a key. What would happen if

(i) a current is passed through coil B by plugging the key, and

(ii) the current is stopped by removing the plug from the key?

Explain your answer mentioning the name of the phenomena involved.

Solution:

(i) When current is made to pass through coil B, by plugging the key in, for that instant, the

galvanometer connected to coil A shows a deflection, i.e., current passes through coil A as well.

(ii) When current is stopped through coil B by taking the plug of the key out, for that instant, thegalvanometer connected to coil A again shows a deflection, this time, however, in the opposite

direction. That is, a current passes through coil A in the opposite direction.

The observations are made because whenever we change the current in the coil B, the magneticfield associated with it and the coil A in its proximity changes. At the very instant of plugging

the key in or taking the plug out, there is an instantaneous flow of current and a change in themagnetic field associated with the coil B. During this instantaneous moment, the current in coil

B reaches from zero to the maximum or from the maximum to zero. This changing magneticfield of coil B induces a current in the coil A.

The phenomenon is known as electromagnetic induction.


What is a solenoid? Draw the pattern of magnetic field lines of a solenoid through which a

steady current flows. What does the pattern of field lines inside the solenoid indicate?

Solution:

A solenoid is a coil of several circular turns of insulated conducting wire, wrapped closely in the

shape of a cylinder.

Pattern of magnetic field lines of a solenoid through which a steady current flows:

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The pattern of magnetic field lines inside a current-carrying solenoid indicates that the magnetic

field is uniform, i.e., strength of the magnetic field is the same, everywhere inside the solenoid.


What is Hypermetropia (far sightedness)? Draw a ray diagram to show how this defect can be

corrected using a lens.

Solution:

Hypermetropiais a defect of vision in which a person cannot see nearby objects clearly, but has

no problems in seeing distant objects.

Corrected vision for a hypermetropic eye by using a convex lens:


Mention any four limitations in harnessing wind energy on a large scale.

Solution:

Four limitations in harnessing wind energy on a large scale are as follows:

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i) Wind mills or wind energy plants can only be built in places where wind blows at a high speedfor the greater part of a year.

ii) For a large-scale windmill to be productive, the wind speed must be atleast 15 km/h.

iii) A large-scale windmill establishment requires large area of land.

iv) The initial cost of establishment of the farm is quite high.


At what distance should an object be placed from a lens of focal length 25 cm to obtain its image

on a screen placed on the other side at a distance of 50 cm from the lens? What will be the

magnification produced in this case?

Solution:

Given that,

Focal length,f= 25 cm

Image distance, v = 50 cm

Form the lens formula,

Or, u = 50 cm

Magnification,

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The object must be placed 50 cm away from the lens, on the other side to produce a

magnification of 1.


Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electronic shells butdifferent number of electrons in their outermost shell. It was found that elements A and G

combine to form an ionic compound. This compound is added in a small amount to almost allvegetable dishes during cooking. Oxides of elements A and B are basic in nature while those of

E and F are acidic. The oxide of D is almost neutral. Based on the above information answer thefollowing questions:

(i) To which group or period of the periodic table do the listed elements belong?

(ii) What would be the nature of compound formed by a combination of elements B and F?

(iii) Which two of these elements could definitely be metals?

(iv) Which one of the eight elements is most likely to be found in gaseous state at roomtemperature?

(v) If the number of electrons in the outermost shell of elements C and G be 3 and 7 respectively,

write the formula of the compound formed by the combination of C and G.

Solution:

(i) The elements A, B, C, D, E, F, G and H belong to the third period of the periodic table and to

the following groups.

A belongs to group 1

B belongs to group 2

C belongs to group 3

D belongs to group 14

E belongs to group 15

F belongs to group 16

G belongs to group 17

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H belongs to group 18

(ii) The compounds formed by B and F would be ionic in nature.

(iii) Elements A and B are definitely metals.

(iv) Element H is most likely to found in gaseous state at room temperature.

(v) The formula of the compound will be CG3.


No chemical reaction takes place when granules of a solid, A, are mixed with the powder ofanother solid, B. However when the mixture is heated, a reaction takes place between its

components. One of the products, C, is a metal and settles down in the molten state while theother product, D, floats over it. It was observed that the reaction is highly exothermic.

(i) Based on the given information make an assumption about A and B and write a chemical

equation for the chemical reaction indicating the conditions of reaction, physical state ofreactants and products and thermal status of reaction.

(ii) Mention any two types of reactions under which above chemical reaction can be classified.

Solution:

(i) Solid A is assumed to be MnO2 and solid B to be Aluminium (Al).

When the mixture of MnO2 andAl is heated, manganese (Mn) is produced in molten state andaluminium oxide (Al2O3) floats over it. Mn is produced in the molten state as a lot of heat energy

is released in the process.

The chemical equation for the reaction can be written as:

(ii) The types of reaction under which the above reaction is classified are

1. Redox reaction2. Displacement reaction


Name the functional group of organic com

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Science 2005 Set 1