Railways NTPC (Technical Ability) Thermodynamics Question Bank Thermodynamics

  • question_answer
    The mathematical conditions at the critical point for a pure substance would be:

    A) \[\frac{\partial p}{\partial v}<0\,;\,\,\frac{{{\partial }^{2}}p}{\partial {{v}^{2}}}=0\] and \[\frac{{{\partial }^{3}}p}{\partial {{v}^{3}}}=0\]

    B) \[\frac{\partial p}{\partial v}=0\,;\,\,\frac{{{\partial }^{2}}p}{\partial {{v}^{2}}}<0\] and \[\frac{{{\partial }^{3}}p}{\partial {{v}^{3}}}=0\]

    C) \[\frac{\partial p}{\partial v}=0\,;\,\,\frac{{{\partial }^{2}}p}{\partial {{v}^{2}}}=0\] and \[\frac{{{\partial }^{3}}p}{\partial {{v}^{3}}}<0\]

    D) \[\frac{\partial p}{\partial v}=0\,;\,\,\frac{{{\partial }^{2}}p}{\partial {{v}^{2}}}=0\] and \[\frac{{{\partial }^{3}}p}{\partial \,{{v}^{3}}}\,\,=\,\,0\]

    Correct Answer: B

    Solution :

    At the critical point, \[\frac{\partial p}{\partial v}=0,\] \[\frac{{{\partial }^{2}}p}{\partial {{v}^{2}}}<0\]and \[\frac{{{\partial }^{3}}p}{\partial {{v}^{3}}}=0\] As the c.p. the value of \[p\,\,-\,\,v\] curve is maximum


You need to login to perform this action.
You will be redirected in 3 sec spinner