Question

A solution containing Mn²⁺, Fe²⁺, Zn²⁺ and Hg²⁺ with a molar concentration of 10^–3 M each is treated with 10^-16 M sulphide ion solution. Which ions will precipitate first if K_sp of MnS, FeS, ZnS and HgS are 10^-10 , 10^-23, 10^-20 and 10^-54 respectively?

a. FeS 

b. MnS 

c. HgS 

d. ZnS

Answer 1

Correct option  (C) HgS

Explanation:

M ²⁺ + S^2– → MS 

Lower the value K_sp, lower will be solubility. Hence HgS will precipitate first.