MDCAT Chemistry MCQ #2216

MDCAT Chemistry MCQ #2216

1. Question 1

   Q1. A saturated solution of Mg(OH)2 has a pH of 10.0 at 25°C. Based on this information, calculate the solubility product constant (Ksp).

   • A) 1 × 10⁻ⁱ⁲
   • B) 5 × 10⁻ⁱ⁳
   • C) 4 × 10⁻ⁱ⁲
   • D) 1 × 10⁻ⁱ⁵

   Answer: 5 × 10⁻ⁱ⁳

   Explanation: pH 10 means pOH = 4, so [OH-] = 10⁻⁴ M. For Mg(OH)2, [Mg2+] = 0.5 × 10⁻⁴. Ksp = [Mg2+][OH-]² = (0.5 × 10⁻⁴)(10⁻⁴)² = 5 × 10⁻ⁱ⁳. Option A is a common calculation error.