AB crystallizes in a body centred cubic lattice with edge length ‘a’ equal to 387 pm. The distance between two oppositely charged ions in the lattice is

Options

(a) 335 pm
(b) 250 pm
(c) 200 pm
(d) 300 pm

Correct Answer:

335 pm

Explanation:

For a bcc lattice,
2(r⁺+r⁻) = √3 a
where r⁺ = radius of cation
r⁻ = radius of anion
a = edge length
.·. (r⁺+r⁻) = √3 ⨯ 387/2
= 335.142 pm ≈ 335 pm.