Question

what are stannates &plumbates

Answer 1

Stannates refer to compound of tin (sn) stannic acid (sn (oh) 4) the formal precursor to stannates, does not exist and is actually a hydrate of sno2.
Plumbates is a salt having one of several lead - containing oxoanions. These are formed by reaction of lead (4)oxide pbo2, with alkali. It contain either hydrated plumbate anion, pb(OH) 2-/6,or anhydrous anions pbo4-/4.