JEE Main 2025 Chemistry question
x mg of (molar mass = 58) is required to be dissolved in 1.0 L of water to produce a pH of 10.0 at 298 K. The value of x is mg. (Nearest integer) (Given: is assumed to dissociate completely in )
Answer: 3
Solution
pH=10 → [OH⁻]=10⁻⁴ M. [Mg(OH)2] = 0.5×10⁻⁴ M. Mass = 0.5×10⁻⁴ × 58 × 1000 mg = 2.9 mg ≈ 3 mg.