Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved to extinguish a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

The evolved gas which extinguishes a burning candle is carbon dioxide \(CO_2 \).
During chemical reaction,
Since, one of the compounds formed during this reaction is calcium chloride and as carbon dioxide is formed when dilute hydrochloric acid reacts with a metal carbonate producing effervescence , it means the metal compound is calcium carbonate \(CaCO_3 \). Hence, the compound A is calcium carbonate.

\( CaCO_3 (s) + 2HCl(aq) \)

\( ↓ \)

\( CaCl_2 (aq) + CO_2 (g) + H_2 O(l) \)