GATE Overflow for GATE XE - Recent questions and answers in Properties of Pure Substances

GATE XE 2026 | Question: 84

Tue, 24 Feb 2026 15:40:40 +0000

Which of the following is/are example(s) of a pure substance at $25^{\circ} \mathrm{~C}$ and $101$ $\mathrm{kPa}$?

Gaseous oxygen
Mixture of liquid water and water vapor
Mixture of liquid water and gaseous oxygen
Homogenous mixture of gaseous oxygen and water vapor

GATE XE 2026 | Question: 99

Tue, 24 Feb 2026 15:38:48 +0000

A rigid and impermeable tank has only moist air with a specific humidity of $0.025 \mathrm{~kg}_{\text {water-vapor }} / \mathrm{kg}_{\text{dry-air}}$ at $30^{\circ} \mathrm{C}$ and $101$ $\mathrm{kPa}$. The air is heated to $90^{\circ} \mathrm{C}$. Assume moist air to behave as an ideal gas. The relative humidity (in $\%$) of the heated air is $\_\_\_\_$ (rounded off to two decimal places).

Saturation pressure of water at $30^{\circ} \mathrm{C}$ is $4.25$ $\mathrm{kPa}$ and at $90^{\circ} \mathrm{C}$ is $70.18$ $\mathrm{kPa}$.

GATE XE 2025 | Question: 96

Sun, 04 May 2025 19:05:51 +0000

A rigid tank of $300 \: \mathrm{litre}$ capacity contains $3 \: \mathrm{kg}$ of oxygen (molar mass $=32 \mathrm{~kg} / \mathrm{kmol}$ ) at $25^{\circ} \mathrm{C}$. If oxygen behaves as an ideal gas, the pressure (in $\mathrm{kPa}$ ) inside the tank is $\_\_\_\_\_\_$ (rounded off to two decimal places).

Use: Universal gas constant $\left(R_{u}\right)=8.314 \mathrm{~kJ} / \mathrm{kmol}-\mathrm{K}$

GATE XE 2025 | Question: 98

Sun, 04 May 2025 19:05:47 +0000

For a pure substance that expands on freezing, which of the following statement(s) is/are $\textsf{CORRECT}$?

Temperature of the liquid phase can be lower than the temperature at the triple point
Critical pressure is equal to the pressure at the triple point
Highest pressure at which the vapour phase can exist is the pressure at the triple point
Highest temperature at which solid-liquid phase change can happen is the temperature at the triple point

GATE XE 2025 | Question: 104

Sun, 04 May 2025 19:05:35 +0000

A piston-cylinder assembly having $250 \: \mathrm{mm}$ diameter contains $0.01 \: \mathrm{kg}$ of water vapor at $1 \: \mathrm{MPa}$ and $200^{\circ} \mathrm{C}$. The specific volume of the vapor is $0.20602 \mathrm{~m}^{3} / \mathrm{kg}$. The system expands as per the relation $\text{p} \text{V}^{n}=$ constant, where $\text{p}$ is pressure and $\text{V}$ is volume. The expansion of water vapour displaces the piston by $50 \: \mathrm{mm}$. If the final pressure is $0.35 \: \mathrm{MPa}$, the value of the exponent $(n)$ is $\_\_\_\_\_\_\_$ (rounded off to two decimal places).

GATE XE 2025 | Question: 106

Sun, 04 May 2025 19:05:32 +0000

A steam boiler contains saturated water vapour at $200^{\circ} \mathrm{C}$. After a certain period, the temperature of the boiler drops to $110^{\circ} \mathrm{C}$. Assume that all the valves of the boiler are closed and the energy is lost as heat to the surroundings. The ratio of mass of liquid to the mass of vapour is $\_\_\_\_\_\_\_$ (rounded off to two decimal places).

Saturated volume of vapour phase at $200{ }^{\circ} \mathrm{C}=0.127 \mathrm{~m}^{3} / \mathrm{kg}$

Saturated volume of vapour phase at $110^{\circ} \mathrm{C}=1.210 \mathrm{~m}^{3} / \mathrm{kg}$

Saturated volume of liquid phase at $110^{\circ} \mathrm{C}=0.001 \mathrm{~m}^{3} / \mathrm{kg}$

GATE XE 2025 | Question: 151

Sun, 04 May 2025 15:30:18 +0000

Consider that specific heat $\left(0\right.$ to $\left.50^{\circ} \mathrm{C}\right)$ of water, water vapour and air remains constant: $4.48,1.88$ and $1.0 \mathrm{~kJ} /\left(\mathrm{kg}{ }^{\circ} \mathrm{C}\right)$, respectively. Assuming, the heat energy required to convert $1 \: \mathrm{kg}$ of water to water vapour at $0^{\circ} \mathrm{C}$ is $2000 \: \mathrm{kJ}$, the enthalpy (in $\mathrm{kJ} / \mathrm{kg}$ dry air) of atmospheric air containing $0.05 \: \mathrm{kg}$ water vapour per $\mathrm{kg}$ dry air at $50^{\circ} \mathrm{C}$ is $\_\_\_\_\_\_\_\_$. (rounded off to $1$ decimal place).

GATE XE 2024 | Question: 81

Sun, 21 Jul 2024 16:41:39 +0000

The figure shows four different processes labeled $1,2,3$, and $4$ for the same closed system containing an ideal gas. The curves labeled $T_{1}, T_{2}$, and $T_{3}$ are isotherms. For which one of the these four processes, the magnitude of internal energy change is the highest?

Process $1$
Process $2$
Process $3$
Process $4$

GATE XE 2024 | Question: 85

Sun, 21 Jul 2024 16:41:35 +0000

Following data is for an actual vapour compression refrigeration cycle.

Enthalpy at compressor inlet: $246 \mathrm{~kJ} / \mathrm{kg}$

Enthalpy at compressor exit: $286 \mathrm{~kJ} / \mathrm{kg}$

Heat load on the evaporator: $158 \mathrm{~kJ} / \mathrm{kg}$

The enthalpy at the exit of the condenser in $\mathrm{kJ} / \mathrm{kg}$ is ________ $\text{(rounded off to the nearest integer)}$.

GATE XE 2024 | Question: 86

Sun, 21 Jul 2024 16:41:34 +0000

A rigid tank, initially at $1$ bar and $300$ K, contains $5$ moles of $\mathrm{O}_{2}, 4$ moles of $\mathrm{N}_{2}$, and 3 moles of $\mathrm{H}_{2}$. From this tank, $2$ moles of $\mathrm{O}_{2}$ are removed keeping the temperature constant. Assuming ideal gas bchaviour, the final partial pressure of $\mathrm{O}_{2}$ (in bar) inside the tank is _______ $\text{(rounded off to three decimal places)}$.

Use $R=8.314 \mathrm{~J} / \mathrm{mol} . \mathrm{K}$

Molecular weights of $\mathrm{H}_{2}, N_{2}$ and $\mathrm{O}_{2}$ are $2 \mathrm{~g} / \mathrm{mol}, 28 \mathrm{~g} / \mathrm{mol}$, and $32 \mathrm{~g} / \mathrm{mol}$ respectively.

GATE XE 2023 | Question: 79

Wed, 14 Feb 2024 18:09:06 +0000

\begin{tabular}{|l|l|}
\hline Q.89 & Which of the following is an extensive property of a system? \\
\hline

& Density \\
\hline
& Pressure \\
\hline
& Temperature \\
\hline
& Total mass
\end{tabular}

GATE XE 2023 | Question: 84

Wed, 14 Feb 2024 18:09:01 +0000

\begin{tabular}{|c|c|}
\hline Q. 94 & \begin{tabular}{l}
An insulated rigid closed tank of $2 \mathrm{~m}^{3}$ internal volume contains saturated liquid- \\
vapor mixture of water at $200^{\circ} \mathrm{C}$. The quality of the mixture is 0.75 . The mass of \\
the mixture in the tank is $\mathrm{kg}$ (rounded off to one decimal place). \\
Use the following data for water:
\end{tabular} \\
\hline & At $200{ }^{\circ} \mathrm{C}: \quad v_{f}=0.001156 \mathrm{~m}^{3} / \mathrm{kg}, v_{f g}=0.12620 \mathrm{~m}^{3} / \mathrm{kg}, v_{g}=0.12736 \mathrm{~m}^{3} / \mathrm{kg}$ \\
\hline
\end{tabular}

GATE XE 2023 | Question: 85

Wed, 14 Feb 2024 18:08:59 +0000

Q. 95 A rigid closed tank contains $2 \mathrm{~kg}$ of an ideal gas at $500 \mathrm{kPa}$ and $350 \mathrm{~K}$. A valve is opened, and half of the mass of the gas is allowed to escape. Then the valve is closed. If the final pressure in the tank is $300 \mathrm{kPa}$, the final temperature in the tank is $\mathrm{K}$ (in integer).

GATE XE 2023 | Question: 93

Wed, 14 Feb 2024 18:08:52 +0000

Q. 103 A rigid tank of $2 \mathrm{~m}^{3}$ internal volume contains $5 \mathrm{~kg}$ of water as a saturated liquid-vapor mixture at $400 \mathrm{kPa}$. Half of the mass of the saturated liquid in the tank is drained-off while maintaining constant pressure of $400 \mathrm{kPa}$ in the tank. The final quality of the mixture remaining in the tank is (rounded off to two decimal places).
Use the following data for water:
At $400 \mathrm{kPa}: v_{f}=0.001084 \mathrm{~m}^{3} / \mathrm{kg}, v_{f g}=0.46138 \mathrm{~m}^{3} / \mathrm{kg}, v_{g}=0.46246 \mathrm{~m}^{3} / \mathrm{kg}$

GATE XE 2023 | Question: 97

Wed, 14 Feb 2024 18:08:48 +0000

Q. 107
In an air-conditioning system, air enters at $20{ }^{\circ} \mathrm{C}$ and $30 \%$ relative humidity at a steady rate of $30 \mathrm{~m}^{3} / \mathrm{min}$ in a humidifier and it is conditioned to $25^{\circ} \mathrm{C}$ and $60 \%$ relative humidity. Assuming entire process takes place at pressure of 100 $\mathrm{kPa}$, the mass flow rate of the steam added to air in the humidifier is $\mathrm{kg} / \mathrm{min}$ (rounded off to three decimal places).

Use the following property data:
At $20^{\circ} \mathrm{C}$ and $25^{\circ} \mathrm{C}$, saturation pressures of water are $2.3392 \mathrm{kPa}$ and $3.1698 \mathrm{kPa}$, respectively.
For air, $R=0.287 \mathrm{~kJ} / \mathrm{kg}-\mathrm{K}$