Thermodynamics practice · Medium

An ideal heat engine exhausting heat at ${27^ \circ }C$ is to have 25% efficiency. It must take heat at

Which is the correct statement

If the door of a refrigerator is kept open, then which of the following is true

Which of the following the scalar quantity is

Which of the following process is reversible?

The quantity of heat required to raise one mole through one degree kelvin for a monoatomic gas at constant volume is

A rigid diatomic ideal gas undergoes an adiabatic process at room temperature. The relation between temperature and volume for this process is $T{V^x} =$ constant, then $x$ is

A certain mass of gas at $273K$ is expanded to 81 times its volume under adiabatic condition. If $\gamma = 1.25$ for the gas, then its final temperature is

A hypothetical gas expands adiabatically such that its volume changes from 08 litres to 27 litres. If the ratio of final pressure of the gas to initial pressure of the gas is $\frac{16}{81}$. Then the ratio of $\frac{C_{p}}{C_{v}}$ will be

(A): Heat flows always from a hotter body to a colder body by itself.
(R): Without an external aid heat cannot flow from colder body to a hotter body.

An engineer claims to have made an engine delivering $10kW$ power with fuel consumption of $1g/s$. The calorific value of the fuel is $2kcal/g$. Is the claim of the engineer

A carnot engine takes 300 calories of heat from a source of 500 K and rejects 150 calories of heat to the sink. The temperature of the sink is

A system is taken from a given initial state to a given final state along various paths represented on a $P-V$ diagram. The quantity that is independent of the path is:

When a small amount of heat $\Delta Q$ is added to an enclosed gas, then increase in internal energy and external work done are related as

Assertion: Between states $\left(\mathrm{P}_1, \mathrm{V}_1, \mathrm{T}_1\right)$ and $\left(\mathrm{P}_2, \mathrm{V}_2, \mathrm{T}_2\right)$, work done in two step process is more than work done in one step process.
Reason: Work done is a path function.

In gases of diatomic molecules, the ratio of the two specific heats of gases ${C_P}/{C_V}$ is

The efficiency of a Carnot engine is $60 \%$. If the temperature of source is $127^{\circ} \mathrm{C}$. The sink must be maintained at

The specific heat of a gas in an isothermal process is

In which thermodynamic process, volume remains same?

(A): The adiabatic exponent $\left(\gamma=\frac{C_p}{C_v}\right)$ of adiatomic gas is less than that of a mono atomic gas
(R): The molecules of mono atomic gas more degrees of freedom.

One gram of water (volume $=1 \mathrm{~cm}^3$ ) becomes 1671 $\mathrm{cm}^3$ of steam when boiled at a pressure of one atmosphere . Latent heat of vaporization at this pressure is $539 \mathrm{~cal} / \mathrm{gm}$. Compute the work done. $\left[1 \mathrm{~atm}=1.013 \times 10^5 \mathrm{Nm}^{-2}\right.$ ]

Choose the correct statement

The slopes of isothermal and adiabatic curves are related as

Assertion: The efficiency of a heat engine can be unity.
Reason: Efficiency of heat engine is fundamental limitation given by first law of thermodynamics.

Statement-I: Monoatomic, diatomic and polyatomic gases are adiabatically compressed such that compression ratio is $\left(\frac{P_2}{P_1}\right)$. Then monoatomic gas will have maximum final volume out of these three gases.
Statement-II: Monoatomic gas has least degree of freedom.

A carnot engine takes $3 \times {10^6}\,\,cal$ of heat from a reservoir at ${627^0}C$ and gives it to a sink at ${27^0}C$. The work done by the engine is,

The relation between two specific heats of a gas is

One mole of oxygen is expanded from a volume $1 \mathrm{~L}$ to $5 \mathrm{~L}$ at a constant temperature $T=280 \mathrm{~K}$. The change in internal energy is:

An ideal gas A and a real gas B have their volumes increased from V to 2V under isothermal conditions. The increase in internal energy

(A): A room can not be cooled by opening the door of a refrigerator in a closed room
(R): Heat flows from lower temperature (refrigerator) to higher temperature (room).