Given: Radius of cation Mg^{2+} (r+ ) = 65 pm

Radius of anion S^{2−} (r^{−} ) = 184 pm

To find: i. The coordination number of MgS = ?

ii. Structure of MgS = ?

Formula:

Radius ratio = Radius of the cation/ Radius of the anion

Calculation:

From formula,

Since the radius ratio lies in between 0.225 – 0.414

**The coordination number of MgS is 4. And the structure of MgS is Tetrahedral. **