0.92 g of `Ag_(2)CO_(3)` is heated strongly beyond its melting point . After heating the amount of residue is

2.76 g of Ag_2CO_3 on being heated yields a residue weighing

92 gm mixture of CaCO_(3) "and" MgCO_(3) was heated strongly in an open vessel. After complete decomposition of the carbonates it was found that the weight of residue left behind is 48g. Find the mass of MgCO_(3) in grams in the mixture.

When orthoboric acid (H_(3)BO_(3)) is heated strongly the residue left is