Question

Which one of the following processes involve chemical reactions?
(i) Filling of LPG gas under pressure in gas cylinders
(ii) Liquefaction of air
(iii) Rusting of an iron object
(iv) Ripening of fruits

Answer 1

A process that leads to chemical change by the transformation of one or more substances into new substances is known as a chemical reaction.

The filling of LPG gas under pressure in gas cylinders and liquefaction of air do not involve any chemical reaction. These are physical changes as no new products are formed. But corrosion of metals, rusting of iron objects, and ripening of fruit involves a chemical reaction.