Question

A solution of NH₄Cl and NH₃ has pH = 8.0. Which of the following hydroxides may be precipitated when this solution is mixed with equal volume of 0.2 M of metal ion.
(a) Ba(OH)₂ ($K_{sp}$ = 1.1 x 10⁻⁴)
(b) Mg(OH)₂ ($K_{sp}$ = 3.5 x 10⁻⁴)
(c) Fe(OH)₂ ($K_{sp}$ = 8.1 x 10⁻¹⁶)
(d) Ca(OH)₂ ($K_{sp}$ = 2.1 x 10⁻⁵)

Answer 1

the answer must be option b