List of top Physics Questions on Thermodynamics

Identify the characteristics of an adiabatic process in a monatomic gas. (A) Internal energy is constant. (B) Work done in the process is equal to the change in internal energy. (C) The product of temperature and volume is a constant. (D) The product of pressure and volume is a constant. (E) The work done to change the temperature from $ T_1 $ to $ T_2 $ is proportional to $ (T_2 - T_1) $. Choose the correct answer from the options given below:

The internal energy of air in $ 4 \, \text{m} \times 4 \, \text{m} \times 3 \, \text{m} $ sized room at 1 atmospheric pressure will be $ \times 10^6 \, \text{J} $. (Consider air as a diatomic molecule)

One mole of an ideal monatomic gas at absolute temperature $ T $ undergoes free expansion to double its original volume, so that the entropy change is $ \Delta S_1 $. An identical amount of the same gas at absolute temperature $ 2T $ undergoes isothermal expansion to double its original volume, so that the entropy change is $ \Delta S_2 $. The value of $ \frac{\Delta S_1}{\Delta S_2} $ (in integer) is:

When 80 J of heat is supplied to a gas at constant pressure, if the work done by the gas is 20 J, then the ratio of the specific heat capacities of the gas is

A refrigerator of coefficient of performance 5 that extracts heat from the cooling compartment at the rate of 250 J per cycle is placed in a room. The heat released per cycle to the room by the refrigerator is

If the internal energy of 3 moles of a gas at a temperature of 27 °C is 2250R, then the number of degrees of freedom of the gas is (R - Universal gas constant)

The work done by 6 moles of helium gas when its temperature increases by $ 20^\circ \text{C} $ at constant pressure is (Universal gas constant = $ 8.31 \, \text{J mol}^{-1} \, \text{K}^{-1} $)

A small quantity of water of mass 'm' at temperature $ \theta^\circ \text{C} $ is mixed with a large mass 'M' of ice which is at its melting point. If 's' is the specific heat capacity of water and 'L' is the latent heat of fusion of ice, then the mass of ice melted is

In a Carnot engine, if the absolute temperature of the source is $ 25% $ more than the absolute temperature of the sink, then the efficiency of the engine is

If a heat engine and a refrigerator are working between the same two temperatures $T_1$ and $T_2$ ($T_1>T_2$), then the ratio of efficiency of heat engine to coefficient of performance of refrigerator is

If the ratio of specific heats of a gas at constant pressure and at constant volume is $\gamma$, then the number of degrees of freedom of the rigid molecules of the gas is

The fundamental limitation to the coefficient of performance of a refrigerator is given by

During adiabatic expansion, if the temperature of 3 moles of a diatomic gas decreases by $50^\circ \text{C}$, then the work done by the gas is
(R - Universal gas constant)

A Carnot heat engine absorbs 600 J of heat from a source at a temperature of 127°C and rejects 400 J of heat to a sink in each cycle. The temperature of the sink is

If the values of the temperature of a body in Fahrenheit and Celsius scales are in the ratio of 13 : 5, then the temperature of the body is

A spherical black body of radius 12 cm at a temperature of $T$ K radiates a power of 400 W. If the radius of the sphere is doubled and absolute temperature is halved, then the power radiated by the body is

If two temperatures on Celsius scale differ by $ 25^\circ $, then the difference of those two temperatures on Fahrenheit scale is

If a Carnot engine working between the temperatures $300 \, \text{K}$ and $600 \, \text{K}$ has work output of $800 \, \text{J}$ per cycle, then the heat supplied to the engine from source per cycle is

During adiabatic expansion process, if the temperature of 4 moles of a monoatomic gas is decreased by $100^\circ C$, then the work done by the gas is
(Universal gas constant $R = 8.3 \, \text{J/mol·K}$)

At constant pressure, if the work done by a gas is 40% of the increase in the internal energy of the gas, then the specific heat capacity of the gas at constant volume is
(Universal gas constant $R = 8.3 \, \text{J mol}^{-1} \text{K}^{-1}$)

500 g of water at a temperature of 73 °C is mixed with 45 g of steam at a temperature of 100 °C. The ratio of the initial mass of steam and the mass of steam at equilibrium of the mixture is

The heat to be supplied to 20 g of oxygen to increase its temperature from 27 $^\circ$C to 59 $^\circ$C at constant pressure is (Universal gas constant = 8.3 J mol$^{-1}$ K$^{-1}$)

If the coefficient of performance of a refrigerator is 5 and the temperature inside it is -20 °C, then the temperature of its surroundings is

Four moles of a diatomic gas at a temperature of 927 $^\circ$C expands adiabatically such that its volume increases by 3100%. The work done by the gas is (Universal gas constant = 8.3 J mol$^{-1}$ K$^{-1}$)

If four moles of hydrogen and two moles of helium form a gaseous mixture, then the molar specific heat capacity of the mixture at constant pressure is