Q. pH of a saturated solution of Ba(OH)₂ is 12. The value of solubility product (Ksp) of Ba(OH)₂ is
A) 5.0 × 10⁻⁶
B) 3.3 × 10⁻⁷
C) 5.0 × 10⁻⁷
D) 4.0 × 10⁻⁶
Explanation
[Solution from source] pH 12 means pOH = 2 and [OH⁻] = 10⁻² M, so [Ba²⁺] = 5 × 10⁻³ M. Ksp = [Ba²⁺][OH⁻]² = 5 × 10⁻³ × (10⁻²)² = 5 × 10⁻⁷. Writing 4s³ with s = 10⁻² wrongly treats [OH⁻] as the solubility, giving 4 × 10⁻⁶. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.