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KVPY Sample Paper KVPY Stream-SX Model Paper-8

  • question_answer
    The process with negative entropy change is:

    A) Dissociation of \[CaS{{O}_{4}}(s)\] to \[CaO(s)\] and \[S{{O}_{3}}(g)\]

    B) Sublimation of dry ice

    C) Dissolution of iodine in water

    D) Synthesis of ammonia from \[{{N}_{2}}\] and \[{{H}_{2}}\]

    Correct Answer: D

    Solution :

    • \[CaS{{O}_{4}}(x)\xrightarrow[{}]{{}}CaO(s)+S{{O}_{3}}(g)\]
    • \[C{{O}_{2}}(s)\xrightarrow[{}]{{}}C{{O}_{2}}(g)\]
    • \[{{I}_{2}}\xrightarrow[{}]{{}}{{I}_{2}}(aq)\]
    • \[{{N}_{2}}(g)+3{{H}_{2}}(g)\xrightarrow[{}]{{}}2N{{H}_{3}}(g)\]
    • \[{{N}_{2}}(g)+3{{H}_{2}}2N{{H}_{3}}(g)\]
    • \[\Delta S=2\Delta {{S}_{N{{H}_{3}}}}-[\Delta {{S}_{{{N}_{2}}}}+3\Delta {{S}_{{{H}_{2}}}}]\]
    There is decrease in number of moles of \[N{{H}_{3}},\] entropy is decreasing.


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