Question

What is the valency of an element of which the equivalent weight is $12$ and the specific heat is $0.25$ ?

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

Answer: (B)

Specific heat $\times$ Atomic weight $=6.4$
(Dulong and Petit law)
Atomic weight $=\frac{6.4}{\text{ specific heat }}=\frac{6.4}{0.25}$
Atomic weight $=Ew\times$ valency $=25.6$
Valency $=\frac{\text{ Atomic weight }}{Ew}=\frac{25.6}{12}=2$
(Valency is always a whole number)