#### 11th Standard Physics Heat and Thermodynamics English Medium Free Online Test One Mark Questions with Answer Key 2020 - 2021

11th Standard

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Physics

Time : 00:20:00 Hrs
Total Marks : 20

20 x 1 = 20
1. The graph between volume and temperature in Charles’ law is

(a)

an ellipse

(b)

a circle

(c)

a straight line

(d)

a parabola

2. When food is cooked in a vessel by keeping the lid closed, after some time the steam pushes the lid outward. By considering the steam as a thermodynamic system, then in the cooking process

(a)

Q > 0, W > 0,

(b)

Q < 0, W > 0,

(c)

Q > 0, W < 0,

(d)

Q < 0, W < 0,

3. A hot cup of coff ee is kept on the table. Aft er some time it attains a thermal equilibrium with the surroundings. By considering the air molecules in the room as a thermodynamic system, which of the following is true

(a)

ΔU > 0, Q = 0

(b)

ΔU > 0, W < 0

(c)

ΔU > 0, Q > 0

(d)

ΔU = 0, Q > 0

4. Identify the state variables given here?

(a)

Q, T, W

(b)

P, T, U

(c)

Q, W

(d)

P, T, Q

5. The efficiency of a heat engine working between the freezing point and boiling point of water is

(a)

6.25%

(b)

20%

(c)

26.8%

(d)

12.5%

6. 1 mole of a gas with $\gamma =\frac { 7 }{ 5 }$  is mixed with 1 mole of gas with $\gamma =\frac { 5 }{ 3 }$ then value of g of the resulting mixture is

(a)

$\frac { 7 }{ 5 }$

(b)

$\frac { 2 }{ 5 }$

(c)

$\frac { 3 }{ 2 }$

(d)

$\frac { 12 }{ 7 }$

7. One kg of a diatomic gas is at a pressure of 8 x 104 N/m2 the density of the gas is 4kglmg What is the energy of the gas due to its thermal mole

(a)

3 x 104 J

(b)

5. x 104

(c)

6 x 104 J

(d)

7 x 104 J

8.  Surface of the lake is at 2°C and depth of the lake is 20m find the temperature of the bottom of the lake

(a)

20C

(b)

30C

(c)

40C

(d)

none of the above

9. Graph of specific heat at constant volume for a mono atomic gas is

(a)

(b)

(c)

(d)

10. In an adiabatic system which is true?

(a)

${ P }^{ \gamma }{ T }^{ \gamma -1 }$ = Constant

(b)

${ P }^{ \gamma }{ T }^{ 1-\gamma }$ = Constant

(c)

${ PT }^{ \gamma }$ = Constant

(d)

${ P }^{ 1-\gamma }{ T }^{ \gamma }$ = Constant

11. Universal gas constant is

(a)

Cp/Cv

(b)

Cp - Cv

(c)

Cp + Cv

(d)

Cv/Cp

12. A process in which the temperature of working substance remains constant during its expansion or compression

(a)

isothermal

(b)

(c)

isobaric

(d)

isochoric

13. The specific heat of water is

(a)

1.817

(b)

25.12

(c)

4.187

(d)

none

14. When two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other. This is

(a)

Kelvin Planck law

(b)

first law of thermodynamics

(c)

zeroth law of thermodynamics

(d)

second law of thermodynamics

15. The coefficient of volume expansion of a solid is x times the coefficient of superficial. expansion. Then x is

(a)

1.5

(b)

2

(c)

2.5

(d)

3

16. A block of wood is floating on water at 0oC with a certain volume V above water level. The temperature of water is slowly raised to 20oC. How does the volume V change with the rise of temperature?

(a)

remain unchanged

(b)

decrease continuously

(c)

decrease till 4°C and then increase

(d)

increase till 4°C and then decrease

17. A steel rod of length 25 cm has a cross-sectional area of 0.8 cm2. The force required to stretch this rod by the same amount as the expansion produced by heating it through woe is (coefficient of linear expansion of steel is 10-5/oC and Young's modulus of steel is 2 x 1010 N/m2)

(a)

40 N

(b)

80 N

(c)

120 N

(d)

160 N

18. A perfect gas at 27°C is heated at constant pressure so as to double its volume. The temperature of the gas becomes.

(a)

54°C

(b)

150K

(c)

327°C

(d)

327K

19. Two vessels A and B contain the same ideal gas. The volume of B is twice that of A, the pressure in B is twice that in A and the temperature of B is twice that of A. The ratio of the number of gas molecules in A and B is

(a)

1 : 2

(b)

2:1

(c)

1: 4

(d)

4:1

20. The pressure of a gas contained in a closed vessel is increased by 0.4% when heated by 1°C. The initial temperature was

(a)

250 K

(b)

250°C

(c)

25 K

(d)

25oC