Question

$2$ g of a divalent metal combines with $0.16$ g of oxygen. Molecular weight of its oxide is:

• A. 200
• B. 108
• C. 100
• D. 216

Answer 1

Answer: (D)

216

Since the metal and oxygen are involved in the same reaction, the ratio of their weights used will be equal to the ratio of their equivalent weights.

$Equivalentmass=\frac{Weightofthemetal}{Weightofoxygen}\times 8$

$=$ $\frac{2}{0.16}\times 8$ $=100$

Since the metal is divalent, Molecular formula $=MO$

.
Atomic mass of metal$=$ Equivalent mass $\times$ valency $=100\times 2=200$

Molecular mass $=$ Atomic mass of metal + Atomic mass of O

$=200+16$

$=216$