Physics Questions: Paper - 13

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Sr. No.

Physics Model Question Paper 13: (For Class 11 and 12 and Pre-Medical/Engineering Entrance)

Answers

1.

1 curie represents

(A) 1 disintegration per second

(B) 106 disintegrations per second

(C) 3.7 1010 disintegrations per second

(D) 3.7 107 disintegrations per second

Answer: (C)

2.

1.56 105 J of heat is conducted through a 2 m2 wall of 12 cm thick in one hour. Temperature difference between the two sides of the wall is 20C. The thermal conductivity of the material of the wall is

(in W m1 K1)

(A) 0.11

(B) 0.13

(C) 0.15

(D) 1.2

Answer: (B)

3.

310 J of heat is required to raise the temperature of 2 moles of an ideal gas at constant pressure from 25C to 35C. The amount of heat required to raise the temperature of the gas through the same range at constant volume is

(A) 452J

(B) 276J

(C) 144J

(D) 384J

Answer: (C)

4.

A 1250 W heater operates at 115 V. What is the resistance of the heating coil?

(A) 1.6 W

(B) 13.5 W

(C) 1250 W

(D) 10.6 W

Answer: (D)

5.

A 20 cm length of a certain solution causes right handed rotation of 38. A 30 cm length of another solution causes left handed rotation of 24. The optical rotation caused by 30 cm length of a mixture of the above solutions in the volume ratio 1 : 2 is

(A) right handed rotation of 3

(B) left handed rotation of 3

(C) right handed rotation of 14

(D) left handed rotation of 14

Answer: (A)

6.

A and B are two metals with threshold frequencies 1.8 1014HZ and 2.2 1014Hz. Two identical photons of energy 0.825 eV each are incident on them. Then photoelectrons are emitted in

(A) A alone

(B) B alone

(C) in both A and B

(D) in neither A nor B

(Take h = 6.6 10-34 Js)

Answer: (A)

7.

A balloon is rising vertically up with a velocity of 29ms-1. A stone is dropped from it and it reaches the ground in 10 seconds. The height of the balloon when the stone was dropped from it is (g = 9.8 ms-2)

(A) 100 m

(B) 200 m

(C) 400 in

(D) 150 m

Answer: (B)

8.

A body floats in water with 40% of its volume outside water. When the same body floats in an oil, 60% of its volume remains outside oil. The relative density of oil is

(A) 0.9

(B) 1.0

(C) 1.2

(D) 1.5

Answer: (D)

9.

A body is moving with velocity 30 m/s towards east. After 10 seconds its velocity becomes 40 m/s towards north. The average acceleration of the body is

(A) 5 m/s2

(B) 1 m/s2

(C) 7 m/s2

(D) 7 m/s2

Answer: (A)

10.

A body of mass 6 kg is acted upon by a force which causes a displacement in it given by x = metre where t is the time in second.

The work done by the force in 2 seconds is

(A) 12 J

(B) 9J

(C) 6 J

(D) 3 J

Answer: (D)

11.

A box is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t is proportional to

(A)

(B)

(C)

(D) t2

Answer: (C)

12.

A boy standing at the top of a tower of 20 m height drops a stone. Assuming g = 10 ms2, the velocity with which it hits the ground is

(A) 5.0 m/s

(B) 10.0 m/s

(C) 20.0 m/s

(D) 40.0 m/s

Answer: (C)

13.

A bullet moving with a speed of 100 ms-1 can just penetrate two planks of equal thickness. Then, the number of such planks penetrated by the same bullet when the speed is doubled in will be _______.

(A) 4

(B) 8

(C) 6

(D) 10

Answer: (B)

14.

A Carnot engine has efficiency 25%. It operates between reservoirs of constant temperatures with temperature difference of 80C. What is the temperature of the low-temperature reservoir?

(A) 25C

(B) 25C

(C) 33C

(D) 33C

Answer: (C)

15.

A Carnot's engine operates with source at 127C and sinks at 27C. If the source supplies 40 kJ of heat energy, the work done by the engine is

(A) 1 kJ

(B) 4 kJ

(C) 10 kJ

(D) 30 kJ

Answer: (C)