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

  • question_answer Rearrange the following (I to IV) in the order of increasing masses and choose the correct answer from A, B, C and D (Atomic mass: N=14, O=16, Cu=63). 1 molecule of oxygen 1 atom of nitrogen \[1\times {{10}^{-10}}\]g molecular weight of oxygen \[1\times {{10}^{-10}}\]g atomic weight of copper

    A)                 II<I<III<IV           

    B)                 IV<III<II<I

    C)                 II<III<I<IV           

    D)                 III<IV<I<II

    Correct Answer: A

    Solution :

               (I)  1 molecule of oxygen                    \[\because \]   \[6\times {{10}^{23}}\] molecule has mass \[=32gm\]                    \[\therefore \]   1 molecule of \[{{O}_{2}}\] has mass \[=\frac{32}{6\times {{10}^{23}}}\]                                                                     \[=5.3\times {{10}^{-23}}gm\]                    (II)  1 atom of nitrogen                    \[\because \]   \[2\times 6\times {{10}^{23}}\]atoms of \[{{N}_{2}}\]has mass = 28gm                    \[\therefore \]   1 atom of \[{{N}_{2}}\]has mass    \[=\frac{28}{2\times 6\times {{10}^{23}}}\]                                                                 \[=2.3\times {{10}^{-23}}gm\]                    (III) \[1\times {{10}^{-10}}g\]molecular weight of oxygen                          g atomic weight \[=2\times 1\times {{10}^{-10}}=2\times {{10}^{-10}}g\]                    (IV) \[1\times {{10}^{-10}}g\]atomic weight of copper                                 So, order of increasing masses \[\text{II}<\text{I}<\text{III}<\text{IV}\].

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