Salt 'P', commonly used in bakery products, on heating gets converted into another salt 'Q' which itself is used for the removal of hardness of water and a gas 'R' is evolved. The gas 'R' when passed through freshly prepared lime water turns milky. Identify 'P', 'Q' and 'R', giving chemical equation for the justification of your answer.

Explanation

Salt is a sodium bicarbonate `NaHCO_(3)` (as it used in bakery products and gives `Na_(2)CO_(3)` on heating). Salt B is sodium carbonate `Na_(2)CO_(3)` (it is used for removal of hardness of water )Gas C is carbon dioxide `CO_(2)` (as it turns lime water milky).
This can be shown as follows.
`2NaHCO_(3)overset(Heat)rarrNa_(2)CO_(3)+H_(2)O+CO_(2)uparrow`