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NEET AIPMT SOLVED PAPER 1999

  • question_answer
                    In the reaction \[S(s)+\frac{3}{2}{{O}_{2}}(g)\xrightarrow{{}}S{{O}_{3}}(g)+2x\,kcal\] and \[S{{O}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)\xrightarrow{{}}S{{O}_{3}}(s)+y\,kcal\] the heat of formation of \[S{{O}_{2}}\] is:              

    A)                                                                                                                                         \[(x+y)\]

    B)              \[(x-y)\] 

    C)              \[(2x+y)\]              

    D)              \[(2x-y)\]

    Correct Answer: D

    Solution :

                    \[(i)\,S(s)+\frac{3}{2}{{O}_{2}}(g)\rightleftharpoons S{{O}_{3}}(g)+2x\,kcal\]                 (ii)  By inverse second equation   \[S{{O}_{3}}(s)\rightleftharpoons \,S{{O}_{2}}(g)+\frac{1}{2}{{O}_{2}}(g)-y\,kcal\]                 on addition  \[S(s)+{{O}_{2}}(g)\rightleftharpoons S{{O}_{2}}(g)+(2x-y)\,kcal\]                 Hence, heat of formation of \[S{{O}_{2}}\,is\,(2x-y)\,kcal\].


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