Thermodynamics practice · Medium

In thermodynamics, heat and work are:

The specific heat of an ideal gas for an isothermal process is

An engine is supposed to operate between two reservoirs at temperature ${727^0}C\,\,and\,\,{227^0}C$ . The maximum possible efficiency of such an engine is

The internal energy of an ideal gas increases during an isothermal process when the gas is

The molar specific heat at constant pressure for a monoatomic gas is

$n$ 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

Assertion: A heat engine is the reverse of a refrigerator.
Reason: A refrigerator cannot work without some external work done on the system.

(A): An adiabatic process is an isoentropic process.
(R): Change in entropy is zero in case of adiabatic process.

An ideal gas in a piston cylinder arrangement is to be taken from a temperature of $500 {~K}$ to a temperature of $600 {~K}$. Which of the thermodynamic process given in options should be used so that the final state of $600 {~K}$ is achieved using a minimum energy input from outside?

The change of entropy, when heat is absorbed by the gas is:

In a Carnot engine, when ${T_2} = 0\,^\circ C\,\,\,\mathrm{and}\;\,\,{T_1} = 200\,^\circ C$ its efficiency is  ${\mathrm{\eta }_1}\mathrm{\;}\,\,\mathrm{and\;}\,\,\,\mathrm{when}\;\,\,\,{T_1} = 0\,^\circ C\;\,\,\mathrm{and}\,\,\;{T_2} = - 200\,^\circ C\;,$ its efficiency is ${\mathrm{\eta }_2}$, then what in ${\eta _1}/{\eta _2}?$

The theory of refrigerator is based on

An engine takes in compressed steam at ${127^ \circ }C$ and rejects it at ${47^ \circ }C$ . Efficiency of the engine is

In which of the processes, does the internal energy of the system remain constant?

The $\Delta H_f^{\circ}$ for $\mathrm{CO}_2(\mathrm{~g}), \mathrm{CO}(\mathrm{g})$ and $\mathrm{H}_2 \mathrm{O}(\mathrm{g})$ are $-393.5,-110.5$ and $-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The standard enthalpy change (in $\mathrm{kJ}$ ) for the reaction,
$\mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g}) \longrightarrow \mathrm{CO}(\mathrm{g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g})$ is

In an isobaric process, $\Delta Q=\frac{\gamma K}{\gamma-1}$, where $\gamma$ is $\boldsymbol{C}_{\boldsymbol{p}} / \boldsymbol{C}_{\boldsymbol{v}}$ What is $K$ ?

An ideal gas at pressure $2.5 \times 10^5 \mathrm{~Pa}$ and temperature $300 \mathrm{~K}$ occupies $100 \mathrm{cc}$. It is adiabatically compressed to half its original volume. Calculate (a) the final temperature and (b) the work done by the gas in the process. Take $\gamma=1.5$.

The work done, W during an isothermal process in which 1 mole of the gas expands from an initial volume ${V_1}$to a final volume ${V_2}$ is given by (R=gas constant, T=temperature)

In an isothermal expansion

Temperature of $100 \mathrm{gm}$ water is changed from $0^{\circ} \mathrm{C}$ to $3^{\circ} \mathrm{C}$ in this process, heat supplied to water will be (specified heat of water $=1 \mathrm{~cal} \mathrm{~g}^{-1}{ }^{\circ} \mathrm{C}^{-1}$

The specific heat of an ideal gas varies with temperature $T$ as

If a system undergoes contraction of volume, then the work done by the system is

(A): $C_p$ is always greater than $C_V$ in gases.
(R): Work done at constant pressure is more than at constant volume.

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 $- 273^\circ C$ 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 $\eta = \left( {1 - \frac{{{T_2}}}{{{T_1}}}} \right)$.
In the light of the above statements, choose the correct answer from the options given below

A given mass of a gas is compressed isothermally until its pressure is doubled. It is then allowed to expand adiabatically until its original volume is restrored and is pressure is then found to be 0.75 of its initial pressure. The ratio of the specific heats of the gas is approximately

A thermally insulated vessel contains an ideal gas of molecular mass $M$ and ratio of specific heats 1.4. Vessel is moving with speed $v$ and is suddenly brought to rest. Assuming no heat is lost to the surrounding and vessel temperature of the gas increases by ($R$ = Universal gas constant)

A carnot engine, having efficiency of $\eta = \frac{1}{{20}}$ as heat engine, is used as a refrigerator. If the work done on the system is 20 J, the amount of energy absorbed from the reservoir at lower temperature is

A sample of gas expands from volume ${V_1}$to ${V_2}$ . The amount of work done by the gas is maximum when the expansion is

The volume of an ideal diatomic gas is doubled isothermally, the internal energy

The first law of thermodynamics is based on the law of conservation of