• # 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

(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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