Summer vacation homework

Biology

Class xii

Q 1. Prepare the investigatory project on assigned topic ?

Q 2. Do questions from past 10 year papers of cbse for ch 1 to 5 ?

Q 3. Learn the notes of all 5 chapters?

Holiday Homework 2019-20

Subject: Physics Class XII(Sc)

1) Draw an equipotential surface in a uniform electric field.

2) Show that electric potential is the line integral of electric field.

3) A point charge +Q is kept in the vicinity of uncharged conducting plate. Sketch electric field

lines between the charge and the plate.

4) Deduce an expression for potential energy of a system of four point charges brought from

infinity to their respective positions in the presence of external electric field.

5) Briefly explain the principle of a capacitor. Derive an expression for the capacitance of a

parallel plate capacitor, whose plates are separated by a dielectric medium.

6) Three point charges of +2μC, -3 μC and -3 μC are kept at the vertices A,B and C respectively

of an equilateral triangle of si9des 20 cm. what should be the sign and magnitude of charge

to be placed at the midpoint M of side BC so that charge at A remains in equilibrium.

7) A small sphere of radius r1 and charge q1 is enclosed by a spherical shell of radius r2 and

charge q2. Show that if q1 is positive, charge will necessarily flow from the sphere to the

shell (when the two are connected by a wire), no matter what the charge q2 on the shell is.

8) Two capacitors with capacitance C1 and C2are charged to potentials V1 and V2 respectively

and then connected in parallel. Calculate the common potential across the combination, the

charge on each capacitor, the electrostatic energy stored in the system and the change in

electrostatic energy from the initial value.

9) Derive the expression for potential energy of an electric dipole placed in a uniform electric

field.

10) Derive the expressions for electric field intensity due a dipole

a) At an axial point

b) At an equatorial point.

11) Calculate electric potential at a point due to an electric dipole.

12) State and prove Gauss’s law in electrostatics. Find the electric field intensity at a point due

to an infinitely charged plane sheet.

13) Solve the NCERT exercise of chapter 1 from question no 1.1 to 1.24. 14) Solve the NCERT exercise of chapter 2 form question no 2.1 to 2.11.

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Class XIIA Session 2019-2020

Sub,Chemistry

LIST OF INVESTIGATORY PROJECTS ALLOTED

GROUP 1 To study the presence of insecticide and pesticide in various food and vegetables.

ROLL NO. 1,2,3,4

GROUP2 Adulterants in food

ROLL NO.5, 6, 7, 8

GROUP3 Study of quantity of casein present in different samples of milk.

ROLL NO.9, 10, 11, 12

GROUP4 Comparative study on the content of cold drinks

ROLL NO.13, 14, 15, 16, 17

GROUP5 Preparation of soyabean milk and its comparison with natural milk.

ROLL NO.18, 19,20,21,22

SUMMER VACATION H.W (2019-20)

CLASS-XII A

SUBJECT: CHEMISTRY

1. For the reaction 2N2O5 (g) →4NO2 (g) +O2 (g),the rate of formation of NO2 (g) is 2.8 x10-3Ms-1.

Calculate the rate of disappearance of N2O5 (g).

2. Calculate the freezing point of a solution containing 60g of glucose (Molar mass=180gmol-1)

in 250g of water. (Kf of water=1.86Kkgmol-1).

3. Give reasons for the following:-

(a)Measurement of osmotic pressure method is preferred for the determination of molar

masses of macromolecules such as proteins and polymers.

(b) Aquatic animals are more comfortable in cold water than in warm water.

4. Elevation of boiling point of 1M KCl solution is nearly double than that of 1M sugar solution.

Why?

5.A first order reaction is 50% completed in 40 minutes at 300K and in 20 minutes

at320K.Calculatetheactivationenergyofthereaction.(Given:log2=0.3010,log4=0.6021,R=8.314JK-

1mol-1).

6. Write the cell reaction and calculate the e.m.f. of the following cell at 298K:-

Sn(s)|Sn2+(0.004M)||H+(0.020M)|H2(g)(1bar)|Pt(s)

(Given:E0Sn2+

/Sn=-0.14V)

7. Give reasons: - (i) On the basis of E0values, O2 gas should be liberated at anode but it is Cl2

gas which is liberated in the electrolysis of aqueous NaCl.

(ii) Conductivity of CH3COOH decreases on dilution.

8. For the reaction

2AgCl(s) +H2 (g) (1atm) →2Ag(s) +2H+ (0.1M) +2Cl-(0.1M)

∆G0= -43600J at 250C

Calculate the emf of the cell. [log10-n= -n]

9. Define fuel cell and write its two advantages.

10. What is the effect of adding a catalyst on (a) Activation energy (Ea) and (b) Gibbs energy

(∆G) of a reaction?

11. Write the name of the cell which is generally used in hearing aids. Write the reactions taking

place at the anode and the cathode of this cell.

12. The cell in which the following reaction occurs:

2Fe3+(aq) +2I-(aq) →2Fe2+(aq) +I2(s)

has E0cell=0.236V at 298K.Calculate the standard Gibbs energy of the cell reaction.(Given

1F=96,500C mol-1).

13. How many electrons flow through a metallic wire if a current of 0.5A is passed for 2hours?

(Given: 1F=96,500C mol-1).

14.A first order reaction takes 20 minutes for 25%decomposition.Calculate the time when 75%

of the reaction will be completed.(Given:log2=0.3010,log3=0.4771,log4=0.6021).

15. A 10% solution (by mass)of sucrose in water has a freezing point of 269.15K.Calculate the

freezing point of 10% glucose in water if the freezing point of pure water is 273.15K. Given:

(Molar mass of sucrose =342gmol-1) (Molar mass of glucose=180 gmol-1).

16. Define the following terms (i) Molality (m) (ii) Abnormal molar mass.

17.30g of urea (M=60g mol-1) is dissolved in 846 g of water. Calculate the vapour pressure of

water for this solution if vapour pressure of pure water at 298K is 23.8 mm Hg.

18. Write two differences between ideal solutions and non-ideal solutions.

19. Write the name of the cell which is generally used in inverters. Write the reactions taking

place at the anode and the cathode of this cell.

20. Write the name of the cell which is generally used in transistors. Write the reactions taking

place at the anode and the cathode of the cell.

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कें द्रीय विद्यालय ओ.एन.जी.सी. वििसागर, असम ग्रीष्मािकाि हते ुगहृकायय

सत्र – 2019 – 2020

कक्षा – १२ अ,ब,स, विषय - वहन्दी

आपके विद्यालय में आयोवजत िार्षयक समारोह का प्रवतिेदन तैयार कीवजए |

फ़ीचर लेखन क्या ह ै? ककसी एक विषय पर फ़ीचर वलवखए |

आलेख लेखन क्या ह ै?ककसी एक विषय पर आलेख वलवखए|

हाल ही में आपके द्वारा पढ़ी गई ककसी एक पुस्तक की समीक्षा वलवखए|

'मन के हारे हार ह ैमन के जीते जीत' अथिा 'क्या नहीं कर सकती नारी ' पर एक

वनबंध वलखें ।

ककसी दैवनक पत्र के संपादक को एक पत्र वलवखए , वजसमें वबजली के संकट से

उत्पन्न कठिनाइयों का संक्षेप में िर्यन ककया गया हो ।

आत्मपठरचय अथिा पतंग कविता का विल्प सोंदयय स्पष्ट करें l