JEE Main & Advanced Chemistry Some Basic Concepts of Chemistry Question Bank Atomic Molecular and Equivalent masses

  • question_answer The sulphate of a metal M contains 9.87% of M. This sulphate is isomorphous with \[ZnS{{O}_{4}}.7{{H}_{2}}O\]. The atomic weight of M is                                                [IIT 1991]

    A)                 40.3       

    B)                 36.3

    C)                 24.3       

    D)                 11.3

    Correct Answer: C

    Solution :

               As the given sulphate is isomorphous with \[ZnS{{O}_{4}}.7{{H}_{2}}O\] its formula would be \[MS{{O}_{4}}.7{{H}_{2}}O\].m is the atomic weight of M, molecular weight of \[MS{{O}_{4}}.7{{H}_{2}}O\] \[=m+32+64+126\] \[=m+222\]                    Hence % of M\[=\frac{m}{m+222}\times 100\]\[=9.87\](given)  or                    \[100m=9.87m+222\times 9.87\]or \[90.13m=222\times 9.87\]                                 or \[m=\frac{222\times 9.87}{90.13}=24.3\].

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