1 ) answer : (c) 0.1 M NaOH
explanation:
Hg (OH)2 <-----------------> Hg+2 + 2OH-
NaOH ---------------------> Na+Â Â Â + OH-
due to common ion the equilibrium shifts to the left so
solubility of Hg(OH)2 decreases
2) answer : (a) It will be more soluble in acidic
water
CaF2 <----------------> Ca+2Â Â + 2F-
HCl <---------------->Â Â H + Cl
H + F- --------------> HF
so F- ions are removed by acid H+ . so that will be decrease in
concentraion of F- in acid .
3)
Mg3(PO4)2 ----------------> 3 Mg+2Â Â + 2 PO4-3
                                       Â
3SÂ Â Â Â Â Â Â Â Â Â Â Â Â Â
2S
Ksp = (3S)^3 (4S)^2 = 108 S^5
3.57 x 10^-6 = 108 S^5
S = 0.032 M
solubility  = 0.032 M
