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
- CaCO3
- Na2CO3
- K2CO3
- CaSO4 2H2O
Answer
(1) CaCO3
Solution
(A)CaCO3 CaO + colourless gasCO2
CaO + H2O (B)Ca(OH)2
Ca(OH)2 + 2CO2 (excess) (C)Ca(HCO3)2
Ca(HCO3)2 (A)CaCO3 + H2O + CO2
Na2CO3 and K2CO3 do not decompose on heating, and gypsum only loses water.
The compound A is CaCO3.
Answer: (1)