A few chemical changes are given below . Write the formulae of the substances involved I those changes.
(a) Baking soda on strong heating produces sodium carbonate , carbon dioxide and water vapour.
(b) Marble on heating gives calcium oxide and carbon dioxide.
( C ) Rust (iron oxide ) is formed when iron reacts with oxygen in the atmospheric air.

Explanation

(a) formula of baking soda a `NaHCO_(3)` . Its chemical name is sodium bicarbonate . The formula of sodium carbonate is `Na_(2)CO_(3)` and those of carbon dioxide and water are `CO_(2) " and " H_(2) O` respectively.
(b) Marble contains calcium carbonate . Its formula is `CaCO_(3)`. The formulae of products are `CaO` (calcium oxide ) and `CO_(2)` (carbon dioxide. )
(c ) Formula of iron and oxygen are Fe and `O_(2) , respectively . The formula of iron oxide formed is `Fe_(2)O_(3)`