JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Heat & Thermodynamics

An insulated cylinder of volume

60 cm^{3}

is filled with a gas at

2 7^{\circ} C

and 2 atmospheric pressure. Then the gas is compressed making the final volume as

20 cm^{3}

while allowing the temperature to rise to

7 7^{\circ} C

. The final pressure is ______ atmospheric pressure.

Answer: 7

Solution

For a fixed mass of ideal gas

\frac{P _{1} V _{1}}{T _{1}} = \frac{P _{2} V _{2}}{T _{2}}

. With

P_{1} = 2 atm

V_{1} = 60 c m^{3}

T_{1} = 2 7^{\circ} C = 300 K

V_{2} = 20 c m^{3}

and

T_{2} = 7 7^{\circ} C = 350 K

P_{2} = \frac{P _{1} V _{1} T _{2}}{T _{1} V _{2}} = \frac{2 \times 60 \times 350}{300 \times 20} = 7 atm .

The final pressure is

7

atmospheric pressure.

JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Integer answer

Practise more: all JEE Main PYQs on Heat & Thermodynamics →

More JEE Main questions on Heat & Thermodynamics

A cylindrical tube $A B$ of length $l$ , closed at both ends contains an ideal gas of 1 mol having molecular weight $M$ . The tube is rotated in a horizontal plane with constant angular velocity $ω$ about an axis perpendicular to $A B$ and passing through the edge at end A, as s …
JEE Main 2026View solution →
Rods $x$ and $y$ of equal dimensions but of different materials are joined as shown in figure. Temperatures of end points $A$ and $F$ are maintained at $10 0^{\circ} C$ and $4 0^{\circ} C$ respectively. Given the thermal conductivity of rod x is three …
JEE Main 2026View solution →
The volume of an ideal gas increases 8 times and temperature becomes $(1/4)^{th}$ of initial temperature during a reversible change. If there is no exchange of heat in this process ( $Δ Q = 0$ ) then identify the gas from the following options (Assuming …
JEE Main 2026View solution →
Consider two boxes containing ideal gases A and B such that their temperatures, pressures and number densities are same. The molecular size of A is half of that of B and mass of molecule A is four times that of B. If the collision frequency in gas B is …
JEE Main 2026View solution →
The r.m.s speed of oxygen molecules at $4 7^{\circ} C$ is equal to that of the hydrogen molecules kept at $____$ $^{\circ} C$ . (Mass of oxygen molecule/mass of hydrogen molecule=32/2)
JEE Main 2026View solution →
A diatomic gas $(γ = 1.4)$ does 100 J of work when it is expanded isobarically. Then the heat given to the gas ______ J.
JEE Main 2026View solution →