Question

In an experiment, $4 \,g$ of $M_{2}O_{x}$ oxide was reduced to $2.8 \,g$ of the metal. If the atomic mass of the metal is $56\,g\,mol^{-1},$ the number of $O$ atoms in the oxide is

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (C)

3

Answer 2

Mass of oxygen in oxide $=4-2.8$ $=1.2 \,g$ E wt. of metal $=\frac{\text { mass of metal }}{\text { mass of oxygen }} \times 8$& $=\frac{2.8}{1.2} \times 8$ $=18.67$ Valency of metal $=\frac{\text { atomic wt. of metal }}{\text { e wt. of metal }}$ $=\frac{56}{18.67}$ (given) $=3$