Question

$1g$ of a metal $M$ which has specific heat of $0.06$ combines with oxygen to form $1.08g$ of oxide. What is the atomic mass of $M$ ?

• A. $100$
• B. $80$
• C. $120$
• D. $110$

Answer 1

Answer: (A)

$100$

Mass of oxygen in oxide $=$ Mass of oxide $-$ Mass of metal

$=1.08g-1g=0.08g$

Equivalent weight of oxygen $=8g$

Since 0.08 g of oxygen combines with 1 g of metal. So, 8 g of oxygen will combine with $=\frac{1}{0.08}\times 8=100g$

Therefore, the equivalent weight of metal is 100 g.

By Dulong petit's law,

Approx. atomic mass of metal $\times$ specific heat $=6.4$

Approx. atomic mass of metal $=\frac{6.4}{0.06}=106.67g$

Valency $=$ Atomic mass ÷ equivalent weight

$=\frac{106.67}{100}=1.0667\approx 1$ (integer)

So, atomic mass $=100g$