Q.

The solubility of AgCl(s) with solubility product 1.6×10-10 in 0.1 M NaCl solution would be          [2016]

1 1.26×10-5 M  
2 1.6×10-9 M  
3 1.6×10-11 M  
4 zero  

Ans.

(2)

Let s be the solubility of AgCl in moles per litre.

AgCl(aq)sAg(aq)+s+Cl(aq)-(s+0.1)

( 0.1 M NaCl solution also provides 0.1 M Cl- ion)

Ksp=[Ag+][Cl-]  ;  1.6×10-10=s(s+0.1)

1.6×10-10=s(0.1)                                    (s<<<<0.1)

s=1.6×10-100.1=1.6×10-9 M