Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : Efficiency of a reversible heat engine will be highest at – 273 ° C temperature of cold reservoir. Reason R : The efficiency of Carnot’s engine depends not only on temperature of cold reservoir but it depends on the temperature of hot reservoir too and is given as η = 1 - T 2 T 1 In the light of the above statements, choose the correct answer from the options given below :

Both A and R are true and R is the correct explanation of A

Both A and R are true but R is NOT the correct explanation of A

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$n$ moles of an ideal gas with constant volume heat capacity $C_{v}$ undergo an isobaric expansion by certain volume. The ratio of the work done in the process, to the heat supplied is:

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Important Questions on Thermodynamics

MEDIUM

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 10th April 2019 Shift 1>Q 63

A cylinder with fixed capacity of

67.2

litre contains helium gas at STP. The amount of heat needed to raise the temperature of the gas by

20 ° C

is:
[Given that

R = 8.31 J m o l^{- 1} K^{- 1}]

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JEE Main

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 10th April 2019 Shift 2>Q 64

When heat

Q

is supplied to a diatomic gas of rigid molecules, at constant volume its temperature increases by

∆ T

. The heat required to produce the same change in temperature, at a constant pressure is:

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JEE Main

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 10th January 2019 Shift 1>Q 65

Three Carnot engines operate in series between a heat source at a temperature

T_{1}

and a heat sink at temperature

T_{4}

(see figure). There are two other reservoirs at temperature

T_{2}

and

T_{3},

as shown, with

T_{1} > T_{2} > T_{3} > T_{4} .

The three engines are equally efficient if:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 10th January 2019 Shift 2>Q 66

2 kg

of a monoatomic gas is at a pressure of

4 \times 10^{4} N m^{- 2}

. The density of the gas is

8 kg m^{- 3}

. What is the order of energy of the gas due to its thermal motion?

EASY

JEE Main

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 10th January 2019 Shift 2>Q 67

Half mole of an ideal monoatomic gas is heated at a constant pressure of

1 atm

from

20 ° C

90 ° C

. Work done by the gas is

(

Gas constant,

R = 8.21 J {mol}^{- 1} K^{- 1}

)

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 12th April 2019 Shift 1>Q 68

Two moles of helium gas is mixed with three moles of hydrogen molecules (taken to be rigid). What is the molar specific heat of mixture at constant volume?

(R = 8.3 J / m o l K)

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 12th April 2019 Shift 1>Q 69

A sample of an ideal gas is taken through the cyclic process

a b c a

as shown in the figure. The change in the internal energy of the gas along the path

c a

- 180 J .

The gas absorbs

250 J

of heat along the path

a b

and

60 J

along the path

b c

. The work done by the gas along the path

a b c

is:

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JEE Main

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 10 - Thermodynamics>JEE Main - 12th April 2019 Shift 2>Q 70

A Carnot engine has an efficiency of

\frac{1}{6} .

When the temperature of the sink is reduced by

62 ℃

, its efficiency is doubled. The temperatures of the source and the sink are, respectively,

n moles of an ideal gas with constant volume heat capacity Cv undergo an isobaric expansion by certain volume. The ratio of the work done in the process, to the heat supplied is:

Important Questions on Thermodynamics

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$n$ moles of an ideal gas with constant volume heat capacity $C_{v}$ undergo an isobaric expansion by certain volume. The ratio of the work done in the process, to the heat supplied is: