Question

what is the valency of oxygen,nitrogen,sulphur,ferrous,ferric,ammonia,sulphate,nitrate,zinc,barium,calcium,carbonate,hydroxide,magnesium,chloride,hydrogen,silver,copper,iron,lead,??

Answer 1

-2;-3;+2;+1;+2;+3;-2!-2;+2;+2;+2;-2;-1;+2;-1;+1;+1;+2;+2;+2