JEE Main & Advanced Physics Kinetic Theory of Gases Question Bank Mock Test - Kinetic Theory of Gases and Laws of Thermodynamics

  • question_answer
    Carbon monoxide is carried around a closed cyclic process\[abc\], in which be is an isothermal process, as shown in figure. The gas absorbs 7000 J of heat as its temperature is increased from 300 K to 1000 K in going from a to b. The quantity of heat ejected by the gas during the process ca is

    A) 4200 J  

    B) 500 J

    C) 9000J  

    D) 9800J

    Correct Answer: D

    Solution :

    [d] \[{{Q}_{ab}}=+7000=\mu {{C}_{v}}(1000-300)\]          ...(i) For the process ca: \[{{T}_{a}}=300K,\]\[{{T}_{c}}={{T}_{b}}=1000K\] \[{{Q}_{Ca}}=\mu {{C}_{P}}(300-1000)=-\mu {{C}_{p}}\times 700\] \[=-\mu ({{C}_{v}}+R)700\]                              ...(ii) For carbon monoxide: \[{{T}_{a}}=300K,\]\[{{T}_{c}}={{T}_{h}}=1000K\] \[{{(\Delta Q)}_{ca}}=\mu {{C}_{p}}(300-1000)=-\mu {{C}_{P}}\times 700\] \[=-\mu ({{C}_{v}}+R)700\] For carbon monoxide: \[\gamma =\frac{7}{5}\] \[{{C}_{v}}=\frac{R}{\gamma -1}=\frac{R}{\frac{7}{5}-1}=\frac{5R}{2}\]                    ...(iii) Hence, form Eq. (i) \[7000=\mu \frac{5R}{2}\times 700\]Or \[\mu R=\frac{20}{5}=4\] \[{{Q}_{ca}}=-(7000+4\times 700)=-9800J\] Negative sing shows that heat is ejected.


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