Solubility of M₂S salt is 3.5 ˣ 10⁻⁶ then find out solubility product

Options

(a) 1.7 ˣ 10⁻⁶
(b) 1.7 ˣ 10⁻¹⁶
(c) 1.7 ˣ 10⁻¹⁸
(d) 1.7 ˣ 10⁻¹²

Correct Answer:

1.7 ˣ 10⁻¹⁶

Explanation:

For reaction. M₂S ⇌ 2M⁺ + S²⁻.

Let solubility = 3.5×10⁻⁶.

Solubility product, K(sp) = [M⁺]²[S²⁻]

= (2s)² s = 4s³

= 4x(3.5×10⁻⁶)³

= 1.7×10⁻¹⁶