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Heat and Thermodynamics question

2018 · 15 Apr · Shift 1 · Q62
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Heat and Thermodynamics question

2018 · 15 Apr · Shift 1 · Q62

JEE MainPhysicsHeat and ThermodynamicsMCQ+4 / −1
One mole of an ideal monoatomic gas is compressed isothermally in a rigid vessel to double its pressure at room temperature, 27∘C.{27^ \circ }C.27∘C. The work done on the gas will be :
  1. A
    300R300R300R
  2. B
    300Rln6300Rln6300Rln6
  3. C
    300Rln2300Rln2300Rln2
  4. D
    300Rln7300Rln7300Rln7
View written solutionFree

Correct answer: C

  1. Given data

    • Number of moles: n=1n=1n=1
    • Process: isothermal
    • Temperature: 27∘C=300 K27^\circ C = 300\,K27∘C=300K
    • Final pressure is double the initial pressure: P2=2P1P_2 = 2P_1P2​=2P1​
  2. Use ideal gas law for isothermal process For an isothermal process of an ideal gas, P1V1=P2V2P_1V_1 = P_2V_2P1​V1​=P2​V2​ Since P2=2P1P_2 = 2P_1P2​=2P1​, P1V1=2P1V2P_1V_1 = 2P_1V_2P1​V1​=2P1​V2​ V1=2V2V_1 = 2V_2V1​=2V2​ V2=V12V_2 = \frac{V_1}{2}V2​=2V1​​

  3. Work done in isothermal compression Work done by the gas in an isothermal process is Wby=nRTln⁡(V2V1)W_{\text{by}} = nRT\ln\left(\frac{V_2}{V_1}\right)Wby​=nRTln(V1​V2​​) Substituting values: Wby=(1)R(300)ln⁡(12)W_{\text{by}} = (1)R(300)\ln\left(\frac{1}{2}\right)Wby​=(1)R(300)ln(21​) Wby=−300Rln⁡2W_{\text{by}} = -300R\ln 2Wby​=−300Rln2

  4. Work done on the gas Work done on the gas is the negative of work done by the gas: Won=−Wby=300Rln⁡2W_{\text{on}} = -W_{\text{by}} = 300R\ln 2Won​=−Wby​=300Rln2

  5. Match with options Therefore, the correct option is: 300Rln⁡2\boxed{300R\ln 2}300Rln2​ which is Option C.

  6. Comparison with stored answer Stored correct answer: C

    Our derived answer also gives C, so they agree.

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