question_answer

The compound A on heating gives a colourless gas and a residue that is dissolved in water to obtain B. Excess of \[C{{O}_{2}}\] 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 A is

A) \[CaC{{O}_{3}}\]              

B) \[N{{a}_{2}}C{{O}_{3}}\]              

C) \[{{K}_{2}}C{{O}_{3}}\] 

D) \[CaS{{O}_{4}}\cdot 2{{H}_{2}}O\]

Correct Answer: A

Solution :

Given, Thus, the compound 'A' must be \[\text{CaC}{{\text{O}}_{\text{3}}}\]and the reactions are as follows