Heat And Thermodynamics - Mechanics - Physics Previous Year Questions

1

2016 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2016

The perfect gas equation for 4g of hydrogen gas is

A

pv = RT

B

pv = 2RT

C

pv = \({1 \over 2}\) RT

D

pV = 4RT

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2

2016 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2016

The temperature of the water of a pond is 0\(^\circ\)C while that of the surrounding atmosphere is \(-\)20\(^\circ\)C. If the density of ice is \(\rho\), coefficient of thermal conductivity is k and latent heat of melting is L, then the thickness Z of ice layer formed increases as a function of time t is

A

\({Z^2} = {{60k} \over {\rho L}}t\)

B

\(Z = \sqrt {{{40k} \over {\rho L}}} t\)

C

\({Z^2} = {{40k} \over {\rho L}}\sqrt t\)

D

\({Z^2} = {{40k} \over {\rho L}}t\)

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3

2016 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2016

If the temperature of the Sun gets doubled, the rate of energy received on the Earth will increase by a factor of

A

2

B

4

C

8

D

16

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4

2016 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2016

If the rms velocity of hydrogen gas at a certain temperature is c, then the rms velocity of oxygen gas at the same temperature is

A

\({c \over 8}\)

B

\({c \over 10}\)

C

\({c \over 4}\)

D

\({c \over 2}\)

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5

2016 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2016

The temperature of a blackbody radiation enclosed in a container of volume V is increased from 100\(^\circ\)C to 1000\(^\circ\)C. The heat required in the process is

A

4.79 \(\times\) 10^\(-\)4 cal

B

921 \(\times\) 10^\(-\)5 cal

C

2.17 \(\times\) 10^\(-\)4 cal

D

None

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6

2017 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2017

Temperature of an ideal gas, initially at 27\(^\circ\)C, is raised by 6\(^\circ\)C. The rms velocity of the gas molecules will

A

increase by nearly 2%

B

decrease by nearly 2%

C

increase by nearly 1%

D

decrease by nearly 1%

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7

2017 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2017

2 moles of an ideal monoatomic gas is carried from a state (p₀, V₀) to state (2p₀, 2V₀) along a straight line path in a p-V diagram. The amount of heat absorbed by the gas in the process is given by

A

3 p₀V₀

B

\({9 \over 2}\) p₀V₀

C

6 p₀V₀

D

\({3 \over 2}\) p₀V₀

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8

2017 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2017

If the pressure, temperature and density of an ideal gas are denoted by p, T and \(\rho\), respectively, the velocity of sound in the gas is

A

proportional to \(\sqrt \rho\), when T is constant

B

proportional to \(\sqrt T\)

C

proportional to \(\sqrt p\), when \(\rho\) is constant

D

proportional to T.

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9

2018 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2018

One mole of a monoatomic ideal gas undergoes a quasistatic process, which is depicted by a straight line joining points \(({V_0},{T_0})\) and \(({2V_0},{3T_0})\) in a V-T diagram. What is the value of the heat capacity of the gas at the point \(({V_0},{T_0})\)?

A

R

B

\({3 \over 2}R\)

C

2R

D

0

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10

2018 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2018

The water equivalent of a calorimeter is 10 g and it contains 50 g of water at 15\(^\circ\)C. Some amount of ice, initially at \(-\) 10\(^\circ\)C is dropped in it and half of the ice melts till equilibrium is reached. What was the initial amount of ice that was dropped (when specific heat of ice = 0.5 cal gm^\(-\)1 \(^\circ\)C^\(-\)1, specific heat of water = 10 cal gm^\(-\)1 \(^\circ\)C^\(-\)1 and latent heat of melting of ice = 80 cal gm^\(-\)1) ?

A

10 g

B

18 g

C

20 g

D

30 g

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11

2018 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2018

Which of the following statement(s) is/are true?

"Internal energy of an ideal gas .............."

A

decreases in an isothermal process.

B

remains constant in an isothermal process.

C

increases in an isobaric process.

D

decreases in an isobaric expansion.

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12

2018 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2018

For an ideal gas with initial pressure and volume p_i and V_i respectively, a reversible isothermal expansion happens, when its volume becomes V₀. Then, it is compressed to its original volume V_i by a reversible adiabatic process. If the final pressure is p_f, then which of the following statement(s) is/are true?

A

p_f = p_i

B

p_f > p_i

C

p_f < p_i

D

\({{{p_f}} \over {{V_0}}}\, = \,{{{p_i}} \over {{V_i}}}\)

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13

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

A horizontal fire hose with a nozzle of cross-sectional area \({5 \over {\sqrt {21} }} \times {10^{ - 3}}{m^2}\) delivers a cubic metre of water in 10s. What will be the maximum possible increase in the temperature of water while it hits a rigid wall (neglecting the effect of gravity)?

A

\(1^\circ\)C

B

\(0.1^\circ\)C

C

\(10^\circ\)C

D

\(0.01^\circ\)C

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14

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

Consider the given diagram. An ideal gas is contained in a chamber (left) of volume V and is at an absolute temperature T. It is allowed to rush freely into the right chamber of volume V which is initially vacuum. The whole system is thermally isolated. What will be the final temperature of the equilibrium has been attained?

A

T

B

\({T \over 2}\)

C

2T

D

\({T \over 4}\)

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15

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

Two identical blocks of ice move in opposite directions with equal speed and collide with each other. What will be the minimum speed required to make both the blocks melt completely, if the initial temperatures of the blocks were \(-\)8\(^\circ\)C each? (Specific heat of ice is 2100 Jkg^\(-\)1K^\(-\)1 and latent heat of fusion of ice is 3.36 \(\times\) 10⁵ Jkg^\(-\)1)

A

840 ms^\(-\)1

B

420 ms^\(-\)1

C

8.4 ms^\(-\)1

D

84ms^\(-\)1

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16

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

Two black bodies A and B have equal surface areas are maintained at temperatures 27\(^\circ\)C and 177\(^\circ\)C respectively. What will be the ratio of the thermal energy radiated per second by A to that by B?

A

4 : 9

B

2 : 3

C

16 : 81

D

27 : 177

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17

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

What will be the molar specific heat at constant volume of an ideal gas consisting of rigid diatomic molecules?

A

\({3 \over 2}R\)

B

\({5 \over 2}R\)

C

R

D

3R

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18

2019 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2019

The initial pressure and volume of a given mass of an ideal gas with \(\left( {{{{C_p}} \over {{C_V}}} = \gamma } \right)\), taken in a cylinder fitted with a piston, are p₀ and V₀ respectively. At this stage the gas has the same temperature as that of the surrounding medium which is T₀. It is adiabatically compressed to a volume equal to \({{{V_0}} \over 2}\). Subsequently the gas is allowed to come to thermal equilibrium with the surroundings. What is the heat released to the surrounding?

A

0

B

\(({2^{\gamma - 1}} - 1){{{p_0}V} \over {\gamma - 1}}\)

C

\(\gamma {p_0}{V_0}In2\)

D

\({{{p_0}V} \over {2(\gamma - 1)}}\)

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19

2020 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2020

An ideal gas undergoes the cyclic process abca as shown in the given p - V diagram


It rejects 50J of heat during ab and absorbs 80J of heat during ca. During bc, there is no transfer of heat and 40J of work is done by the gas. What should be the area of the closed curved abca?

A

30J

B

40J

C

10J

D

90J

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20

2020 · Physics · Mechanics · Heat And Thermodynamics

WB JEE 2020

A container AB in the shape of a rectangular parallelopiped of length 5 m is divided internally by a movable partition P as shown in the figure.


The left compartment is filled with a given mass of an ideal gas of molar mass 32 while the right compartment is filled with an equal mass of another ideal gas of molar mass 18 at same temperature. What will be the distance of P from the left wall A when equilibrium is established?

A

2.5 m

B

1.8 m

C

3.2 m

D

2.1 m

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