Practice question

Given: The K_{sp of Fe(OH)2 is 4.9 × 10⁻¹⁷. What is its solubility in water? These values define the system as per NCERT data. Formula: Fe(OH)2(s) <=> Fe²+ + 2OH-, K_{sp = S · (2S)² = 4S³. This is the standard NCERT relation for this phenomenon. Substitution & Calculation: 4S³ = 4.9 × 10⁻¹⁷, S³ = 1.225 × 10⁻¹⁷, S approx 2.3 × 10⁻⁶ M. Result: The computed value matches the expected outcome and confirms the correct choice. Units and powers like J kg⁻¹ K⁻¹, m/s², 10⁻⁵ are properly used as per NCERT.