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Question Bank No: 1

1. If $α, β$ and $γ$ are coefficient of linear, sperficial and volume expansion respectively.

a)		$\frac{β}{α} = \frac{1}{2}$
b)		$\frac{β}{γ} = \frac{2}{3}$
c)		$\frac{γ}{α} = 3$
d)		$\frac{β}{α} = \frac{γ}{β}$

2. A rigid container with thermally insulated walls contains a coil of resistance 100 $Ω$ , carrying current 1A. change in internal energy after 5 minute will be

a)		0 KJ
b)		10 KJ
c)		20 KJ
d)		30 KJ

3. Which of the following is correct regarding the first law of thermodynamics?

a)		It introduces the concept of the entropy
b)		It introduces the concept of internal energy
c)		It is a restatement of the principle of conservation of energy
d)		It is not applicable to any cyclic process

4. Carnot engine working between 300k and 600k has a work output of 800J per cycle. The amount of heat energy supplied to the engine from the source in each cycle is

a)		800J
b)		1600J
c)		3200J
d)		6400J

5. Latent heat of vaporisation of water is 2240J. If the workdone in the process of vapourisation of 1 gram is 168J. Then increase in internal energy is

a)		2072 J
b)		1904 J
c)		2408 J
d)		2240 J

6. Two spheres made of same material have radii in the ration 1:2 Both are at same temperature. Ratio of heat radiation energy emitted per second by them is

a)		1:2
b)		1:4
c)		1:8
d)		1:16

7. The specific heat of a gas in an isothermal process is

a)		infinite
b)		zero
c)		negative
d)		remains constant

8. Two stars X and Y emit yellow and blue lights respectively. Out of these whose temperature is more

a)		that of X
b)		that of Y
c)		No one
d)		can't say

9. The temperature of a black body is reduced to $\frac{1}{3}$ rd. The amount of radiations emitted by the body will reduce to

a)		$\frac{1}{3}$ time
b)		3 time
c)		9 time
d)		$\frac{1}{81}$ time

10. If the temperature of a hot black body is raised by 5% heat energy radiated would increases by

a)		25%
b)		15%
c)		12.5%
d)		21.55%

11. If L is length, A the area of cross section and K, thermal conductivity. Then the thermal resistance of the block is given by

a)		KLA
b)		1/KLA
c)		L+KA
d)		L/KA

12. The pressure and density of a diatomic gas (r = 7/s) changes from (p,p) to ( $p^{1}, p^{1})$ during an adiabatic change $\frac{p^{1}}{0} = 32$ $\frac{p^{1}}{p} = ?$

a)		32
b)		1/32
c)		128
d)		1/128

13. What is the function of carburetor in petrol engine

a)		filtration of petrol
b)		filtration of air
c)		control the flow of petrol
d)		formation of proper mixture of petrol and air

14. A thermodynamical system return to its initial state. Which of the following is not possible

a)		workdone is zero
b)		workdone is +ve
c)		workdone is -ve
d)		workdone is independent of path followed

15. A refrigerator absorbs 2000 cals of heat from ice trays. If the coefficient of performance is 4. Then the work done by motor is

a)		2100 J
b)		4200 J
c)		8400 J
d)		500 J

16. Thermodynamical system goes from state i( $p_{1} v)$ to (2 $p_{1} v)$ and (ii) ( $p_{1} v)$ to ( $p_{1} 2 v)$ work done in the two cases is

a)		zero,zero
b)		zero, pv
c)		pv, zero
d)		pv, pv

17. One mole of an ideal gas expands adiabatically from an initial temp $T_{1}$ to final temp $T_{2} .$ The work done by gas would be

a)		( $c_{p} - c_{r}) (T_{1} - T_{2})$
b)		$c_{p} (T_{1} - T_{2})$
c)		$c_{r} (T_{1} - T_{2})$
d)		( $c_{p} - c_{r}) (T_{1} + T_{2})$

18. The value of critical temperature in terms of Vander Waals constant a and b is given by

a)		$T_{c} = \frac{8 a}{27 Rb}$
b)		$T_{c} = \frac{27 a}{8 Rb}$
c)		$T_{c} = \frac{a}{27 Rb}$
d)		$T_{c} = \frac{a}{2 Rb}$

19. $Δ w = 0$ For the process

a)		isobaric
b)		isochoric
c)		isothermal
d)		adiabatic

20. A bottle of water at $0^{0}$ c is opened on the surface of the moon. What happens?

a)		water freezes
b)		water will boil
c)		water decompoes into $H_{2} and O_{2}$
d)		none of these happens

21. One gram of ice at $0^{0}$ c is added to 5 gram of water at $10^{0} c .$ Final temperature of mixture is

a)		- $5^{0} c$
b)		$5^{0} c$
c)		$0^{0} c$
d)		none of these

22. The specific heat of ice at $0^{0}$ c melting into water at $0^{0}$ c is

a)		zero
b)		water
c)		more than zero
d)		less than zero

23. Which of the following has the highest specific heat.

a)		Copper
b)		Water
c)		hydrogen
d)		silver

24. The apparent coefficient of expansion of a liquid when heated in a copper vessel is C, and when heated in a silver vessel is S. If A is linear coefficient of expansion of copper, then the linear coefficient of expansion of silver is

a)		$\frac{C + S - 3 A}{3}$
b)		$\frac{C + 3 A - S}{3}$
c)		$\frac{C + S + 3 A}{3}$
d)		$\frac{S + 3 A - C}{3}$

25. The adiabatic elasticity of hydrogen gas ( $γ = 1.4) at NTP is$

a)		1 $\times 10^{5} N / m^{2}$
b)		1 $\times 10^{- 5} N / m^{2}$
c)		1.4N/ $m^{2}$
d)		1.4 $\times 10^{5} N / m^{2}$

26. For an adiabatic expansion of a perfect gas, the value of $Δ P / P is equal to$

a)		$\frac{Δ V}{V}$
b)		$γ \frac{Δ V}{V}$
c)		- $γ \frac{Δ V}{V}$
d)		- $γ^{2} \frac{Δ V}{V}$

27. $C_{p} > C_{v} as in the case of C_{p}$

a)		more heat is required to increase the internal energy
b)		heat is required to do work against external pressure also
c)		more heat is required to do external work
d)		more heat is required to do external work as well as for increase in internal energy

28. A piece of glass is heated to a high temperature and then allowed to cool. If it cracks, a probable reason is the following property of glass

a)		low thermal conductivity
b)		high thermal conductivity
c)		high specific heat
d)		high melting point

29. The thermal conductivity of copper is

a)		less than that of iron
b)		less than that of AI
c)		less than that of wood
d)		more than that of all three given above

30. One gm of ice at $0^{0}$ C is added to 5gm of water at $10^{0}$ C. If the latent heat is 80 cal/gm, the final temperature of the mixture is

a)		$5^{0}$ C
b)		$6^{0}$ C
c)		${- 5}^{0}$ C
d)		none of these

31. Two rods of same material and length have their radii in ratio of 3:1, the ratio of expansion when same amount of heat is supplied will be

a)		6:1
b)		9:1
c)		3:1
d)		12:1

32. no other thermometer is as suitable as a platinum resistance thermometer to measure temperature in the entire range of

a)		$0^{0}$ C to $100^{0}$ C
b)		$100^{0}$ C to $1500^{0}$ C
c)		${- 50}^{0}$ C to $350^{0}$ C
d)		${- 300}^{0}$ C to $600^{0}$ C

33. The temperature range measured by hydrogen gas thermometer is

a)		- $200^{0}$ C to $800^{0}$ C
b)		- $200^{0}$ C to $500^{0}$ C
c)		- $260^{0}$ C to $800^{0}$ C
d)		- $260^{0}$ C to $500^{0}$ C

34. The reading of centigrade thermometer coincides with that of fahrenheit thermometer in a liquid. The temperature of the liquid is

a)		- $40^{0} C$
b)		$0^{0} C$
c)		$100^{0} C$
d)		$300^{0} C$

35. A sample of ideal gas ( $γ = 1.4) is heated at constant pressure . If 100 J of heat is supplied to gas, the work done by the gas is$

a)		28.57J
b)		56.54J
c)		38.92J
d)		65.38J

36. In a certain region of space there are'n' number of molecules per unit volume. The temperature of gas is T. The pressure of gas will be

a)		$\frac{n' T}{R}$
b)		$n' T / K$
c)		n'KT
d)		n'RT

37. Temperature of an ideal gas is 300K. The change in temperature of the gas when its volume changes from $V_{1} to V in the process p = \propto V (where λ is + ve constant) is$

a)		900K
b)		1200K
c)		600K
d)		300K

38. An ideal gas heat engine operates in a carnot cycle between $227^{0} C and 127^{0} C$ .It absorbs 6kcal of heat at higher temperature. The amount of heat in kcal rejected to sink is

a)		4.8
b)		2.4
c)		1.2
d)		6.0

39. The temperature of sink of Carnot engine is $27^{0} C and its efficiency is 25 % . The temperature of source is$

a)		$227^{0} C$
b)		$127^{0} C$
c)		$27^{0} C$
d)		$327^{0} C$

40. A monoatomic gas of n moles is heated from temperature $T_{1} to T_{2} under two different conditions (i) constant volume (ii) constant pressure . The change in internal energy of gas$

a)		move in (i)
b)		more in (ii)
c)		same in both cases
d)		independent of number of moles

41. The equation of state, corresponding to 8 kg of $O_{2}$ is

a)		PV = RT
b)		PV = 8 RT
c)		PV = $\frac{RT}{2}$
d)		PV = $\frac{RT}{4}$

42. The efficiency of the reversible heat engine is $η_{r}$ and that of irreversible heat engine is $η_{i}$ which of the following relations is correct?

a)		$η_{r}$ > $η_{i}$
b)		$η_{r}$ < $η_{i}$
c)		$η_{r}$ = $η_{i}$
d)		$η_{r}$ > 1 and $η_{i}$ < 1

43. A sink, that is a system where heat is rejected is essential for the conversion of heat into work. From which law the above inference follows?

a)		Zeroth
b)		First
c)		Second
d)		Third

44. A black body is at a temperature of 2800 K. The energy of radiation emitted by this object with wavelength between 499 nm and 500nm is $U_{1}$ , between 999 nm and 1000nm is $U_{2}$ and between 1499 nm and 1500 nm is $U_{3}$ . The Wien constant b = 2.80 $\times 10^{6}$ nm K. Then

a)		$U_{1}$ = 0
b)		$U_{3}$ = 0
c)		$U_{1} > U_{2}$
d)		$U_{2} > U_{1}$

45. A gas in an airtight container is heated from $25^{\circ} C$ to $90^{\circ} C$ . The destiny of gas will

a)		Increase slightly
b)		Increase considerably
c)		Remain the same
d)		Decrease slightly

46. 10 gm of ice at ${- 20}^{\circ} C$ is dropped into a calorimeter containing 10 gm of water at $10^{\circ} C$ , the specific heat of water is twice that of ice when equilibrium is reached, the calorimeter will contain

a)		20 gm of water
b)		20 gm of ice
c)		10 gm ice and 10 gm water
d)		5 gm ice and 15 gm water

47. A uniform metal rock is used as a bar pendulum. If the room temperature rises by $10^{\circ} C$ , and the coefficient of linear expansion of the metal of the rod is 2 $\times 10^{- 6}$ per ${}^{\circ}C$ , the period of the pendulum will have percentage increase of

a)		${- 2 \times 10}^{- 3}$
b)		${- 1 \times 10}^{- 3}$
c)		${2 \times 10}^{- 3}$
d)		${1 \times 10}^{- 3}$

48. A thick and a thin wire of same material and same material and same length are heated from $10^{\circ} C$ to $90^{\circ} C$ . Which expands more?

a)		Thick wire
b)		Thin wire
c)		Both show same expansion
d)		None of these

49. Mercury thermometers can be used to measure temperature upto

a)		$100^{\circ} C$
b)		$212^{\circ} C$
c)		$360^{\circ} C$
d)		$500^{\circ} C$

50. The temperature of a room heated by a heater is $20^{\circ} C$ , when outside temperature is ${- 20}^{\circ} C$ and it is $10^{\circ} C$ when the outside temperature is ${- 40}^{\circ} C$ . The temperature of heater is

a)		$60^{\circ} C$
b)		$40^{\circ} C$
c)		$80^{\circ} C$
d)		$100^{\circ} C$