Question

If $N_A$ is Avogadro's number then number of valence electrons in 4.2 g of nitride ions $N^{3-}$ is

• A. 2.4 $N_A$
• B. 4.2$N_A$
• C. 1.6$N_A$
• D. 3.2$N_A$

Answer 1

Answer: (A)

2.4 $N_A$

Answer 2

$14\,g$ of $N^{3-}$ ions have valence electrons $=8N_{A}$ $4.2\,g$ of $N^{3-}$ ions have valence electrons $=\frac{8N_{A}\times 4.2}{14}=2.4\,N_{A}$