Question

On decreasing the pH from 7 to 2, the solubility of a sparingly soluble salt (MX) of a weak acid (HX) increased from 10⁻⁴ mol L⁻¹ to 10⁻³ mol L⁻¹. The pKa of HX is

(A) 3

(B) 4

(C) 5

(D) 2

Answer 1

Correct option is (B) 4

Equation (1)/(2) gives