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

  • question_answer The number of molecules in 4.25 g of ammonia are [Pb. CET 2000]

    A)                 \[0.5\times {{10}^{23}}\]

    B)                 \[1.5\times {{10}^{23}}\]

    C)                 \[3.5\times {{10}^{23}}\]

    D)                 \[1.8\times {{10}^{32}}\]

    Correct Answer: B

    Solution :

               Molecular weight of \[N{{H}_{3}}\] is 17                    According to the mole concept                    \[17\,gm\] \[N{{H}_{3}}\] has molecules \[=6.02\times {{10}^{23}}\]                    \[\therefore \,\,1\,gm\] \[N{{H}_{3}}\] has molecules \[=\frac{6.02\times {{10}^{23}}}{17}\]                    \[\therefore \] \[4.25\,gm\] \[N{{H}_{3}}\] has molecules                                 \[=\frac{6.02\times {{10}^{23}}\times 4.25}{17}=1.5\times {{10}^{23}}\,molecule\]

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