Question

The compound A on heating gives a colourless gas and a residue that is dissolved in water to obtain B. Excess of CO₂ is bubbled through aqueous solution of B, C is formed which is recovered in the solid form. Solid C on gentle heating gives back A. The compound is

(a) CaCO₃

(b) Na₂CO₃

(c) K₂CO₃

(d) CaSO₄.2H₂O

Answer 1

The correct option is: (a) CaCO₃

Explanation:

The reactions can be summarised as follows:

This is possible only when A is CaCO₃. The reactions are as follows :