Thermodynamic processes are indicated in the following diagram. Match the following Column – 1 Column - 2 P. Process I a. Adiabatic Q. Process II b. Isobaric R. Process III c. Isochoric S. Process IV d. Isothermal

P → c , Q → a , R → d , S → b

P → a , Q → c , R → d , S → b

P → c , Q → d , R → b , S → a

P → d , Q → b , R → a , S → c

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A fixed mass of air at $1$ atmospheric pressure is compressed adiabatically to $5$ atmospheres and allowed to expand isothermally to its original volume. The process is represented in which one of the following indicator diagrams?

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Important Questions on Thermodynamics

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

One mole of an ideal diatomic gas undergoes a transition from $A$ to $B$ along a path $AB$ as shown in the figure,

Question Image

The change in internal energy of the gas during the transition is:

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

An ideal gas is compressed to half of its initial volume by means of several processes. Which of the process results in the maximum work done on the gas?

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

One mole of diatomic ideal gas undergoes a cyclic process ABC as shown in figure. The process BC is adiabatic. The temperatures at A, B and C are 400 K, 800 K and 600 K respectively. Choose the correct statement :

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EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

C_{p} - C_{v} = \frac{R}{M}

and

C_{v}

are specific heats at constant pressure and constant volume respectively. It is observed that,

C_{p} - C_{v} = a

for hydrogen gas and

C_{p} - C_{v} = b

for nitrogen gas. The correct relation between

a

and

b

is:

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

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?

HARD

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

The heat capacity of one mole an ideal is found to be

C_{V} = \frac{3 R (1 + a R T)}{2}

where

a

is constant. The equation obeyed by this gas during a reversible adiabatic expansion is:

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

4.0 g

of a gas occupies

22.4

liters at NTP. The specific heat capacity of the gas at constant volume is

5.0 J K^{- 1} m o l^{- 1}

. If the speed of sound in this gas at NTP is

952 m s^{- 1}

, then the heat capacity at constant pressure is

(Take gas constant

R = 8.3 J K^{- 1} m o l^{- 1}

)

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

N

moles of diatomic gas in a cylinder is at a temperature

T

. Heat is supplied to the cylinder such that the temperature remains constant but

n

moles of the diatomic gas get converted into monoatomic gas. The change in the total kinetic energy of the gas is

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

An ideal monoatomic gas occupies a volume of

2 m^{3}

at a pressure of

3 \times 10^{6} Pa .

The energy of the gas is:

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

For a diatomic ideal gas in a closed system, which of the following plots does not correctly describe the relation between various thermodynamic quantities?

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

For a rigid diatomic molecule, the universal gas constant

R = n C_{P}

, where,

C_{P}

is the molar specific heat at constant pressure and

n

is a number. Hence,

n

is equal to

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

A gas is compressed isothermally to half its initial volume. The same gas is compressed separately through an adiabatic process until its volume is again reduced to half. Then:

HARD

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

An engine operates by taking

n

moles of an ideal gas through the cycle

A B C D A

shown in figure. The thermal efficiency of the engine is:

(Take

C_{v} = 1.5 R

, where

R

is gas constant)

Question Image

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

An ideal gas is taken reversibly around the cycle $a - b - c - d - a$ as shown on the T (temperature) - S (entropy) diagram

Question Image

The most appropriate representation of above cycle on a U (internal energy)-V (volume) diagram is

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

An ideal gas has molecules with

5

degrees of freedom. The ratio of specific heats at constant pressure

(C_{p})

and at constant volume

(C_{V})

is:

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

Thermodynamic processes are indicated in the following diagram.

Question Image

Match the following

Column – 1	Column - 2
P. Process I	a. Adiabatic
Q. Process II	b. Isobaric
R. Process III	c. Isochoric
S. Process IV	d. Isothermal

MEDIUM

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

The bulk modulus of a gas is defined as,

B = \frac{- V d P}{d V}

. For an adiabatic process, the variation of

B

is proportional to

P^{n}

. For an ideal gas,

n

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

For the given cyclic process $C A B$ as shown for a gas, the work done is:

Question Image

EASY

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

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}

)

HARD

Physics>Heat and Thermodynamics>Thermodynamics>First Law of Thermodynamics

Consider a spherical shell of radius R at temperature T. The black body radiation inside it can be considered as an ideal gas of photons with internal energy per unit volume

u = \frac{U}{V} \propto T^{4}

and pressure

p = \frac{1}{3} (\frac{U}{V})

. If the shell now undergoes an adiabatic expansion the relation between T and R is:

A fixed mass of air at 1 atmospheric pressure is compressed adiabatically to 5 atmospheres and allowed to expand isothermally to its original volume. The process is represented in which one of the following indicator diagrams?

Important Questions on Thermodynamics

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A fixed mass of air at $1$ atmospheric pressure is compressed adiabatically to $5$ atmospheres and allowed to expand isothermally to its original volume. The process is represented in which one of the following indicator diagrams?