Please provide explanation along with the solution.
In which compound is the valency of lead NOT 2?
(A) PbO2
(B) PbSO4
(C) PbCl2
(D) Pb(OH)2
For this question you have to use the oxidation state rules. So we know that a compound has an overall oxidation state of 0, while oxygen is -2 (unless in peroxide where it's -1 but none of these compounds are peroxides).
So for (a) there is two oxygens so the o2 is 4- but the overall compound has a 0 oxidation state so the lead must be 4+ (Answer is A)
(B) sulphate ion is 2- so lead is 2+
(C) one cl ion is 1- so two cl ions is 2-, thus lead is 2+ Since the overall charges added up need to equal 0 since it's a compound
(D) one oh ion is 1- so two oh ions is 2- so lead is 2+