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) CaSO₄.2H₂O
(b) CaCO₃
(c) Na2CO₃
(d) K₂CO₃
Answers
answer is CaSO4.2H2O
When a compound X, (calcium carbonate) on heating gives a colorless gas (carbon dioxide) and residue (calcium oxide) as a product then residue is dissolved in water to obtain Y (calcium hydroxide) and then excess carbon dioxide is bubbled through aqueous solution of Y (calcium hydroxide) it forms Z (calcium bicarbonate). On gentle heating, Z (calcium bicarbonate) gives back X (calcium carbonate).
When the excess carbon dioxide gas is passed through the calcium hydroxide, it turns milky first due to the formation of the calcium carbonate as a precipitate which is insoluble in water and then become colorless due to the formation of calcium bicarbonate. On passing excess of carbon dioxide gas, the colorless calcium bicarbonate is formed.