AIIMS AIIMS Solved Paper-2000

  • question_answer
    One mole of an Ideal gas for which \[{{C}_{v}}=3/2R\] is heated reversibly at a constant pressure of 1 atm from \[{{25}^{o}}C\] to \[{{100}^{o}}C\]. The \[\Delta H\] is:

    A)  3.775 cal 

    B)                         37.256 cal           

    C)         372.56 cal     

    D)         3725.6 cal

    Correct Answer: C

    Solution :

    We know that \[{{C}_{P}}-{{C}_{V}}=R\] or \[{{C}_{P}}={{C}_{V}}+R\] \[{{C}_{P}}=\frac{3}{2}R+R=\frac{5}{2}R\]                  \[\left[ \because {{C}_{V}}=\frac{3}{2}R \right]\] At constant pressure heat given by one mole gas = \[mS\Delta T\] or \[\Delta H={{q}_{p}}=1\times \frac{5}{2}R(373-298)\] \[=1\times \frac{5}{2}\times 1.987\times 75\] \[=372.56cal\]


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