Question

The element 'M' having equivalent mass $12$, forms an oxide MO. The molar mass of MO is:

• A. $30$
• B. $40$
• C. $20$
• D. $60$

Answer 1

Answer: (B)

$40$

Equivalent mass $=\frac{molarmass}{valency}$

Equivalent mass $=12$

Since it forms an oxide $MO$, its valency must be $+2$

Molar mass of $MO=(12\times 2)+16=24+16=40g$