Q. If the concentration of OH⁻ ions in the reaction Fe(OH)₃(s) ⇌ Fe³⁺(aq) + 3OH⁻(aq) is decreased by 1/4 times, then equilibrium concentration of Fe³⁺ will increase by
A) 4 times
B) 8 times
C) 16 times
D) 64 times
Explanation
[Solution from source] K = [Fe³⁺][OH⁻]³ is constant (the solid does not appear). If [OH⁻] becomes one quarter, [OH⁻]³ falls by 4³ = 64, so [Fe³⁺] must increase 64 times. 4 times ignores the cube from the coefficient 3. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.