If Nₐ is Avagadro number then number of valence electrons in 4.2g of nitride ions (N³⁻) is

Options

(a) 2.4 Nₐ
(b) 4.2 Nₐ
(c) 1.6 Nₐ
(d) 3.2 Nₐ

Correct Answer:

2.4 Nₐ

Explanation:

At weight of nitrogen= 14
No of moles of nitride ion = 4.2/14 = 0.3 mol
= 0.3 x Nₐ nitride ions
One N³⁻ ion contains 8 valence electrons. 5 + 3 due to charge.
Valence electrons = 8 x 0.3 Nₐ = 2.4 Nₐ