Question

Which of the following statement(s) is/are correct regarding ionic compounds?
(C.N. - Coordination number)

• A. For maximum stability, anion-anion should be in contact
• B. Number of anions surrounding any cation is C.N. of cation
  
• C. Number of cation surrounding any cation is C.N. of cation
• D. For maximum stability cation-cation contact should be avoided

Answer 1

Answer: (B), (D)

For maximum stability cation-cation contact should be avoided

Ionic solids have close packed spheres of ions with the hole occupied by ions of another kind.

In ionic compounds for maximum stability, a cation must be surrounded by maximum of anions and vice versa.
Also, Anion-anion and cation-cation contact should be avoided.

Coordination number of cation is the number of anions surrounding any cation.
Coordination number of anion is the number of cations surrounding any anion.

Thus, statement (b) and (d) are correct.