3 CHEMISTRY IN YOUR LIFE - · PDF fileClass-VII Chemistry Question Bank1 3 CHEMISTRY IN YOUR LIFE Question-Answers. Q. 1 (i) What do you understand by the term metal? (ii) State any

1Class-VII Chemistry Question Bank

3 CHEMISTRY IN YOUR LIFEQuestion-Answers.Q. 1 (i) What do you understand by the term metal?

(ii) State any five physical properties of a metal.Ans.(i)The elements which are generally hard solids, have lustre and are

malleable, ductile, tensile and good conductors of heat andelectricity, are called metals.

(ii) The five physical properties of metals are:1. Metals are lustrous.2. Metals are malleable and ductile.3. Metals are sonorous.4. Metals have high melting and boiling points.5. Metals are good conductors of heat and electricity.

Q. 2. (i) Name a metal which is a liquid at room temperature.(ii) Name a metal which can be cut with a knife.

(iii) Name a metal which is lighter than water.(iv) Name a metal which is not malleable.(v) Name the metal which is the best conductor of heat and

electricity.Ans. (i) Mercury (ii) Sodium (iii) Sodium (iv) Zinc (v) SilverQ. 3. State two important uses of the following metals.

(i) Gold (ii) Silver (iii) Copper (iv) Iron(v) Tin (vi) Lead (vii) Zinc (viii) Aluminium

(ix) Magnesium (x) MercuryAns. (i) Gold —

1. It is used for making jewellery.2. It is used in Ayurvedic medicines in the form of thin leaves

or very fine powder.(ii) Silver —

1. It is used for making coins and ornaments.2. It is used for making electrical circuits in very sensitive

electric appliances.(iii) Copper —

1. It is used for making electric wires.

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2. It is used for making utensils, coins and statues.(iv) Iron —

1. It is used in the construction of buildings.2. It is used in making automobiles, railway bridges and many

kinds of machines.(v) Tin —

1. It is used for tinning food cans.2. It is used for making the alloy bronze.

(vi) Lead —1. It is used for making lead acid batteries.2. It is used for making sanitary pipes.

(vii) Zinc —1. It is used for galvanising iron sheets.2. It is used as a negative electrode of dry cells.

(viii) Aluminium —1. Aluminium foils are used for packing food materials,

medicines, etc.2. It is used for making alloys like duralumin and magnalium.

(ix) Magnesium —1. It is used in fire works.2. It is used as a fuse wire in thermite welding.

(x) Mercury —1. It is used in thermometers.2. It is used in dentistry for filling tooth cavities in the form of

gold and silver amalgam.Q. 4. (i) What do you understand by the term non-metal?

(ii) State any five physical properties of a non-metal.Ans. (i) Non-metals are the elements which are either gases or soft solids,

have no lustre and are non-malleable, non-ductile, brittle and badconductors of heat and electricity.

(ii) Physical properties of non-metals are —1. Non-metals are generally gases at room temperature.2. Non-metals do not have lustre.3. Non-metals have a low density.4. Non-metals are brittle.5. Non-metals are generally poor conductors of heat and

electricity.


Q. 5. (i) Name the form of a non-metal which is the hardest andnaturally occurring substance.

(ii) Name a non-metal which is a liquid at room temperature.(iii) Name the form of a non-metal which is good conductor of

electricity.(iv) Name a non-metal which is a greenish yellow gas.(v) Name a non-metal which helps in the growth of plants.

Ans. (i) Diamond (ii) Mercury (iii) Graphite (iv) Chlorine (v) NitrogenQ. 6. Give two uses of the following.

(i) Common salt (ii) Hydrochloric acidAns. (i) Common Salt —

1. It is used in the preservation of meat and fish.2. It is used in the manufacture of baking soda, washing soda,

hydrochloric acid, caustic soda, etc.(ii) Hydrochloric acid —

1. It is used in making bathroom cleansing agent.2. It is used as an important laboratory reagent.

Q. 7. (i) What are fertilisers?(ii) Name: (a) three nitrogenous fertilisers

(b) two phosphatic fertilisers(c) two potash fertilisers.

Ans. Fertilisers — The materials added to the soil, so as to make up for thedeficiency of essential nutrients are called fertilisers.(i) Three nitrogenous fertilisers — Calcium ammonium nitrate, basic

calcium nitrate, urea.(ii) Phosphatic fertilisers — Triammonium phosphate, superphosphate

of lime.(iii) Potash fertilisers — Potassium chloride, potassium nitrate.

Q. 8. State the use/uses of the following substances.(i) Sand (ii) Sodium silicate (iii) Silicons (iv) Blue vitriol (v)Limestone (vi) Gypsum

(vii) Plaster of Paris.Ans. (i) Sand — It is used in the manufacture of glass and cement.

(ii) Sodium silicate — It is used in the preservation of eggs.(iii) Silicons —

1. They are used in the preparation of water-proof clothes.2. In the preparation of non-stick pans.

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3. They are used in polishing waxes.(iv) Blue vitriol — It is a powerful pesticide. It is used for spraying

over citrus trees and grapevines to kill insects.(v) Limestone — It is used in the manufacture of lime, cement and

glass.(vi) Gypsum —

1. It is used to reduce the acidity of soil.2. It is used along with cement for delaying the setting of

cement.(vii) Plaster of Paris —

1. It is used to keep fractured bones in fixed position.2. It is used for casting statues, toys and decorative materials.3. It is used for panelling ceilings of big halls.4. It is used for making blackboard chalk.

Q. 9. (i) Name three classes of organic compounds which are essentialfor human beings.

(ii) A gaseous organic compound which is used as a fuel.Ans. (i) The three classes of organic compounds which are essential for

human beings are:1. Carbohydrate 2. Fats 3. Proteins

(ii) Methane is a gaseous organic compound which is used as fuel.Q. 10. State three major uses of cement.Ans. The three major uses of cement are —

1. It is used for grouting. It gives a very smooth finish on plasteredsurface.

2. Cement mortar, a mixture of cement and sand, is used for joiningbricks.

3. For making reinforced cement concrete (RCC) which is used inthe construction of roofs, bridges, etc.

Q. 11. Give one use of the following kinds of glass.(i) Soda glass (ii) Hard glass

(iii) Optical glass (iv) Borosil glassAns. (i) Soda glass — It is used for making window panes, glass bottles

and glass tumblers.(ii) Hard glass — It is used for making laboratory apparatus.

(iii) Optical glass — It is used for making lenses for spectacles,telescopes, microscopes, etc.


(iv) Borosil glass — It is used for making laboratory apparatus, coffeeflasks, baking bowls, etc.

Q. 12. What do you understand by the following terms?(i) Plastic (ii) Plasticity (iii) Polymer

Ans. (i) Plastic is a man-made material made by the polymerisation ofsimple molecules such as ethene, vinyl chloride, etc.

(ii) Plasticity — The property by virtue of which a substance can bemoulded into various forms is called plasticity.

(iii) Polymer — A polymer is a long chain of similar moleculesformed by the addition of a large number of small molecules.

Q. 13. State four characteristics of plastics.Ans. Four characteristics of plastics are —

(i) There is hardly any effect of chemicals on plastic.(ii) Plastics are non-biodegradable.

(iii) Plastics are insulators.(iv) Plastics are light in weight.

Q. 14. By giving at least three examples, explain clearly what do youunderstand by the following terms.(i) Thermoplastics (ii) Thermosetting plastics

Ans. Thermoplastics — A kind of plastic which can be remoulded intodesired shape by gentle heating is called thermoplastics, e.g., polythene,nylon and polystyrene.Thermosetting plastic — A kind of plastic which can be moulded intoany desired shape on heating but the articles so formed cannot beremoulded further is called thermosetting plastic. For example,bakelite, and melamine.

Q. 15. What is soap? Name the raw materials required for thepreparation of soap.

Ans. Soap is a sodium salt of fatty acid formed by the chemical reactionbetween sodium hydroxide and vegetable oils and fats.

Raw materials needed for the preparation of soap are sodiumhydroxide and vegetable oils.

Q. 16. What is a synthetic detergent?Ans. Detergent is a synthetic cleansing agent, which is chemically sodium

lauryl sulphate.Q. 17. What is the advantage of detergent over soap?Ans. Detergent lathers even in hard water, whereas soap does not.

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Q. 18. Describe how glass is made. Why are glass objects cooled slowly?Ans. Glass is made by melting a mixture of purified sand (silica), sodium

carbonate or potassium carbonate and calcium carbonate, till a clearmass is obtained.

Glass objects are cooled slowly because they crack whensubjected to sudden changes in temperature.

Q. 19. In which materials are glass fibres embedded to make fibre glass?Ans. Glass fibres are embedded in plastic to make fibre glass.Q. 20. Write the names of ingredients used for manufacturing

(i) cement (ii) glass (iii) soap (iv) concrete.Ans. (i) Cement → Limestone and clay.

(ii) Glass → Limestone, soda ash and clay.(iii) Soap → Sodium hydroxide, vegetable oils or fats.(iv) Concrete → Cement and sand.

Q. 21. What are antiseptics?Ans. Disinfectants that can stop the growth of bacteria and can also be used

on the body are called antiseptics.Q. 22. What is glass?Ans. Glass is a substance formed by the solidification of a liquid. It is made

by melting a mixture of sand, sodium carbonate and calcium carbonatetill a clear mass is obtained.

Q. 23. State which non-metal:(i) has a high melting point (ii) has high density.

(iii) is a good conductor of heat and electricityAns. (i) Carbon (ii) Diamond (iii) Graphite

ExercisesA. Give reasons for the following.

1. Copper wires are used in electric cables, but tungsten is not.Ans. Copper is a good conductor of electricity, while tungsten is a bad

conductor of electricity. 2. Clinical thermometers are made of mercury.

Ans. Mercury is a good conductor of heat and expands easily on heating,so it is used in making clinical thermometers.

3. Graphite is used as a lubricant.Ans. Layers of carbon in graphite are held by weak forces and, hence

slide over one another, making graphite slippery. So, it is used as alubricant.


4. Helium is used in weather observation balloons but argon isnot.

Ans. Helium is lighter than air; so it is used in weather observatoryballoons, while argon is heavier than air.

5. Polythene can be reused by heating but bakelite cannot.Ans. Polythene is a thermoplastic which can be remoulded into various

shapes on heating, while bakelite is a thermosetting plastic whichcannot be reused since they do not soften again on heating.

B. Tick ( ) the most appropriate answer.1. Which metal is used in thermometers?

(a) Iron (b) Aluminium (c) Mercury (d) Copper2. Galvanised iron is the iron with a coating

(a) zinc (b) silver (c) gold (d) tin3. Which element is used for filling spaces in oil tanks?

(a) Oxygen (b) Nitrogen (c) Mercury (d) Hydrogen4. What is the common name of CH3COOH?

(a) Table salt (b) Vinegar (c) Blue vitrol (d) Marble5. A homogeneous mixture of a metal with other metals or non-metals

is called(a) a metalloid (b) a compound(c) an alloy (d) none of the above

6. Which one of these is an alloy of copper and tin?(a) Brass (b) Bronze(c) German silver (d) Gun metal

7. A powdered mixture of limestone and clay is called(a) plastic (b) glass (c) cement (d) fertiliser

8. Gypsum(a) delays the setting of cement(b) helps in proper blending and sand(c) maintains the temperature in the clinker(d) none of the above.

9. Ingredients for making glass are(a) limestone, sodium hydroxide and sand (b) limestone and sand(c) limestone, soda ash and sand (d) lime and soda.

10. The process of cooling glass articles slowly to prevent brittleness iscalled(a) cladding (b) annealing (c) finishing (d) saponification.

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11. Which type of glass has a high refractive index?(a) Lead crystal glass (b) Ordinary glass(c) Pyrex glass (d) Photochromatic glass

12. Which of these consists of a long chain of similar molecules linkedtogether?(a) Glasses (b) Polymers (c) Ceramics (d) Fertilisers

13. Linking together small molecules to form large molecules is knownas(a) polymerisation (b) polymony (c) polarisation (d) combination

14. Stunted growth of plants can be controlled by using(a) nitrogenous fertilisers (b) phosphatic fertilisers(c) potash fertiliser(d) both nitrogenous and potash fertiliser

15. Copper metal is used in making(a) electric wires (b) fuse wires(c) filling cavity in teeth (d) preparation of hydrogen

16. Silver amalgam is prepared by dissolving silver in(a) molten copper (b) dilute nitric acid(c) mercury (d) molten gold

17. Bronze is an alloy of(a) copper and tin (b) copper and zinc(c) tin and zinc (d) copper, zinc and tin

18. Glucose saline is used as(a) a soft drink (b) distilled water(c) a rehydrating solution (d) none of the above

19. Ordinary glass consists of(a) asodium silicate (b) calcium silicate(c) mixture of sodium silicate and calcium silicate(d) mixture of lead silicate and calcium silicate

20. A non-metal which is a good conductor of heat and electricity is(a) diamond (b) sulphur (c) graphite (d) phosphorus

21. Chemically, detergent is(a) sodium acetate (b) sodium obate(c) sodium lauryl sulphate (d) sodium carbonate

Ans. 1. (c) 2. (a) 3. (b) 4. (b) 5. (c) 6. (b) 7. (c) 8. (a) 9. (b) 10. (b)11. (a) 12. (b) 13. (a) 14. (a) 15. (a) 16. (c) 17. (d) 18. (c) 19. (c)20. (c) 21. (c).


C. Fill in the blank spaces.1. The brilliant shine over the freshly cut surface of metals is called

......................... .2. The property by virtue of which a substance can bear a lot of

........................ , without breaking is called tensile strength.3. In the form of its very thin leaves or its oxide, ........................ is used

in Ayurvedic medicines.4. Tin is used for making ........................ .5. Graphite is the only non-metal which is a ........................ of electricity.6. Chlorine is a non-metal used for ........................ cotton fabrics.7. Common salt containing small amount of sodium iodide, is called

........................ salt.8. Duralumin is an alloy of 95% aluminium, 4% ............... , 0.5%

manganese and 0.5% magnesium.9. The molecular formula of glucose is ........................ .

10. Graphite and diamond are the ........................ of carbon.11. ........................ is a food preservative.12. ........................ used in making surgical instruments.13. ........................ used as wrappers for packing food items.14. ........................ glass consists of only sodium silicate.15. Many monomers are linked together to form a .................... .16. The substances that can be decomposed by micro-organisms are said to

be ........................ .17. Man-made chemicals used to kill pests are called ................. .18. Drugs used to relieve pain are called ........................ .19. ........................ is the raw material used in making many synthetic dyes.20. ........................ is an example of a nitrogenous fertiliser.21. The most ductile metal is ........................ .22. ........................ and ........................ are energy giving food nutrients.23. An alloy is a ........................ mixture.

Ans. 1. lustre 2. strain 3. silver 4. fusible alloys 5. good conductor6. bleaching 7. iodised 8. copper 9. C6H12O6 10. allotropes11. Citricacid 12. Stainless steel 13. Aluminium foil 14. Water 15. polymer16. biodegradable 17. pesticides 18. analgesics 19. Coal tar 20. Urea21. gold 22. Carbohydrates, fats 23. homogeneous

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D. Define these terms.1. Non-metals 2. Detergent 3. Alloy 4. Insecticides 5. Carbohydrates

Ans. 1. Non-metals — The elements which are non-conducting, non-ductile,non-malleable, brittle and dull in appearance are non-metals.

2. Detergent — A synthetic cleansing agent which can be used in softwater as well as in hard water.

3. Alloy — A homogenous solid mixture of two or more metals or non-metals is called an alloy.

4. Insecticides — The pesticides which are used to kill insects arecalled insecticides.

5. Carbohydrates — Carbohydrates are the complex organic compoundsmade of hydrogen, oxygen and carbon.

E. Name the following.1. A plastic you would use for:

a. Making frying pans b. Packing delicate objectsc. Making dinner plates

Ans. a. Teflon, b. Polythene, c. Melamine.2. A type of glass you would use for:

a. Making window panes b. Making laboratory apparatusc. Making spectacles cum sunglassesd. Making a baking dish e. Making windscreen of a car

Ans. a. Soda glass, b. Hard glass, c. Optical glass, d. Pyrex glass,e. Safety glass.

F. Write true or false in front of the following statements:1. Soap lathers in hard water, but a detergent does not.2. Most of the plastics are resistant to strong acids and alkalis.3. Nylon is an example of thermoplastic.4. Supercooled material formed by slow cooling of silicates of sodium

and calcium is called glass.5. Urea is a potash fertiliser.6. Iodine is a liquid non-metal which is brown in colour.7. Glucose saline is a solution of glucose and common salt in distilled

water.8. Diamond is a crystalline form of carbon which is good conductor of

electricity.9. Copper nitrate, also called ‘blue vitriol’, is a powerful pesticide.

10. Carbohydrates are complex inorganic compounds containing carbonand hydrogen only.


11. Borosil or pyrex glass expands on heating and hence is used formaking laboratory equipments.

12. Clinical thermometers contain mercury.Ans. 1. F 2. T 3. T 4. T 5. F 6. F 7. T 8. F 9. F 10. F

11. F 12. TG. Choose the odd one out. Give reasons for your choice.

1. Oxygen, nitrogen, carbon, goldAns. Gold. Gold is a metal, while others are non-metals.

2. Carbohydrate, fat, protein, hydrogenAns. Hydrogen. Hydrogen is an element, while others are compounds.

3. Iron, brass, bronze, steel, duraluminAns. Iron. Iron is an element, while the rest are alloys.

4. Polyethene, polyvinyl chloride, polystyrene, bakeliteAns. Bakelite. Bakelite is thermosetting plastic, while others are

thermoplastics.5. Bakelite, melamine, formica, polyethene

Ans. Polyethene. Polyethene is thermoplastic, while rest arethermosetting plastics.

6. Urea, ammonium sulphate, ammonium nitrate, potassium nitrate.Ans. Potassium nitrate. It is a potassium fertiliser, while others are

nitrogenous fertilisers.H. Statements given below are incorrect. Write the correct statements.

1. Bronze is a mixture of 10% copper, 80% zinc and 10% tin.Ans. Bronze is a mixture of 80% copper, 18% tin and 2% zinc.

2. Soda water is prepared by dissolving washing soda in water.Ans. Soda water is prepared by dissolving carbon dioxide in water.

3. Urea is an artificial fertiliser, which supplies the nutrient phosphorusto the soil.

Ans. Urea is an artificial fertiliser which supplies the nutrient nitrogen tothe soil.

4. Sodium silicate is used in the preservation of old buildings.Ans. Sodium silicate is used in the preservation of eggs.

5. Plaster of Paris is obtained by heating hydrated calcium carbonate atcontrolled temperature.

Ans. Plaster of Paris is obtained by heating hydrated calcium sulphate atcontrolled temperature.

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6. Limestone and sand are the raw materials for the manufacture ofcement.

Ans. Limestone and clay are the raw materials for the manufacture ofcement.

7. Cement concrete is a slurry of 1 part of gravel, 2 parts of sand and 3parts of cement in water.

Ans. Cement concrete is a slurry of one part of cement, two parts of graveland three parts of sand in water.

8. Thermosetting plastics can be remoulded on gentle heating.Ans. Thermoplastics can be remoulded on gentle heating.

9. NaHCO3 is washing soda.Ans. NaHCO3 is baking soda.

10. Stainless steel is an alloy of iron and carbon.Ans. Stainless steel is an alloy of iron, carbon, chromium and nickel.

11. Iodine is not required in the human diet.Ans. Iodine is required in the human diet.

12. Oxygen is called marsh gas.Ans. Methane is called marsh gas.

13. Soft glass is used to make ovenwares.Ans. Pyrex glass is used to mak ovenwares.

14. Nylon can be used for making non-stick pans.Ans. Teflon can be used for making non-stick pans.

15. Urea is a potash fertiliser.Ans. Urea is a nitrogeneous fertiliser.

16. Chromium oxide gives red colour to glass.Ans. Cuprous oxide gives red colour to glass.

17. Iron oxides give blue colour to glass.Ans. Copper oxide and cobaltous oxide give blue colour to glass.

I. Match Column A with the Column B.Column A Column B

1. Haemoglobin (a) protein2. Argon (b) gas used as a domestic fuel3. DDT (c) bronze4. Alloy (d) chlorine5. LPG (e) light bulb6. Cement (f) mixture of sand, cement, water and gravel


Column A Column B7. Concrete (g) made from limestone and clay8. Plaster of Paris (h) made from soda ash, sand and limestone9. Germicide (i) used as relief from pain

10. Analgesic (j) pesticide11. Glass (k) obtained by heating gypsum12. Polymers (l) fat + NaOH → soap + glycerol13. Thermoplastic (m) softened by heat14. Bakelite (n) thermosetting plastic15. Saponification (o) long chain of similar molecules

Ans. 1. (a) 2. (e) 3. (j) 4. (c) 5. (b) 6. (g) 7. (f) 8. (k) 9. (d) 10. (i) 11.(h) 12. (o) 13. (m) 14. (n) 15. (l)

J. Name the metals from which the following alloys are formed.1. Brass, 2. Stainless steel, 3. Bronze, 4. Duralumin

Ans. 1. Copper, Zinc 2. Iron, chromium, nickel, carbon 3. Copper, tin, zinc4. Aluminium, copper, magnesium, manganese.

K. Give appropriate terms for the following statements.1. A homogeneous mixture of super-cooled molten sodium silicate and

calcium silicate.2. A fertiliser which supplies nitrogen and calcium to the soil.3. A product obtained by mixing caustic soda solution with vegetable oil.4. A kind of plastic which can be remoulded on gentle heating.5. A man-made material used extensively in protecting articles made

from wood and iron.6. A synthetic material used for washing clothes when water is hard.7. A man-made material used in building houses.8. A fertiliser which supplies only nitrogen to the soil.9. The most malleable metal.

10. A metal that is brittle.11. A non-metal that is lustrous.12. A non-metal that is a good conductor of heat and electricity.13. The hardest naturally occurring substance.14. A metal used in making electric cables.15. A liquid non-metal.

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16. A soft metal.17. A metal used as a thermometric liquid. ..................

Ans. 1. Soda glass 2. Calcium ammonium nitrate 3. Soap 4. Thermoplastic5. Paint 6. Detergent 7. Cement 8. Urea 9. Gold 10. Zinc 11. Iodine12. Graphite 13. Diamond 14. Copper 15. Bromine 16. Sodium17. Mercury

L. Give the chemical name and formula of the given compounds.1. Limestone2. Sand3. Gypsum4. Marble5. Blue vitriol6. Plaster of Paris7. Common salt

Ans. 1. Calcium carbonate — CaCO32. Silicon dioxide — SiO23. Calcium sulphate dihydrated — CaSO4.2H2O4. Calcium carbonate — CaCO35. Hydrated copper sulphate — CuSO4.5H2O6. Calcium sulphate hemihydrate — CaSO4.½H2O7. Sodium chloride — NaCl.

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3 CHEMISTRY IN YOUR LIFE - · PDF fileClass-VII Chemistry Question Bank1 3 CHEMISTRY IN YOUR LIFE Question-Answers. Q. 1 (i) What do you understand by the term metal? (ii) State any