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QJEEM23Ph5f57: JEE Main 2023 Physics - Class 11 JEEM23Ph5f57 Solution: Consider two containers A and B containing monoatomic gases at…

Consider two containers A and B containing monoatomic gases at the same Pressure (P), Volume (V) and Temperature (T). The gas in A is compressed isothermally to 18 of its original volume while the gas in B is compressed adiabatically to 18 of its original volume. The ratio of final pressure of gas in B to that of gas in A is

Multiple Choice Options

  • A 18
  • B 832
  • C 4
  • D 8

Step-by-Step Verified Solution

The final pressure of gas in container A after isothermal compression can be found using the equation of state for an ideal gas, PV=nRTPV = nRT , where PP is the pressure, VV is the volume, nn is the number of moles, RR is the gas constant, and TT is the temperature. For an isothermal process, the temperature TT is constant, so the equation becomes P1V1=P2V2P_1V_1 = P_2V_2 .

The final volume is 18\frac{1}{8} of the initial volume, so P2=P1×V1V2=P1×8=8P1P_2 = P_1 \times \frac{V_1}{V_2} = P_1 \times 8 = 8P_1 .

The final pressure of gas in container B after adiabatic compression can be found using the adiabatic equation for an ideal gas, PVγ=constantPV^\gamma = \text{constant} , where γ\gamma is the ratio of the heat capacities, which is 53\frac{5}{3} for a monoatomic gas.

Since V2=V18V_2 = \frac{V_1}{8} , we have P2=P1×(V1V2)γ=P1×853=P1×25=32P1P_2 = P_1 \times \left(\frac{V_1}{V_2}\right) ^ \gamma = P_1 \times 8^\frac{5}{3} = P_1 \times 2^5 = 32P_1 .

The ratio of the final pressure of gas in B to that of gas in A is therefore 32P18P1=4\frac{32P_1}{8P_1} = 4 .

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