• # question_answer 62)   Which of the following pairs have the same number of atoms? (a) $16g$of ${{O}_{2}}(g)$and $4\,g$of ${{H}_{2}}(g)$ (b) $16g$of ${{\text{O}}_{2}}$and $44\,g$of $C{{O}_{2}}$ (c) 28 g of ${{N}_{2}}$ and 32 g of ${{O}_{2}}$ (d) 12 g of C(s) and 23 g of Na(s)

(c, d) (c) Number of atoms of Nitrogen $=\frac{\text{Mass}\,}{\text{Atomic}\,\text{mass}}\times 6.023\times {{10}^{23}}$ $=\frac{28}{14}\times 6.023\times {{10}^{23}}$ $=2\times 6.023\times {{10}^{23}}$ Number of atoms of Oxygen $=\frac{32}{16}\times 6.023\times {{10}^{23}}$ $=2\times 6.023\times {{10}^{23}}$ (d) Number of atoms of Carbon $=\frac{12}{12}\times 6.023\times {{10}^{23}}$ $=6.023\times {{10}^{23}}$ Number of atoms of Sodium $=\frac{23}{23}\times 6.023\times {{10}^{23}}$                 $=6.023\times {{10}^{23}}$