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) Heating platinum wire in the presence of air at a high temperature

[0.8 mark]

• A. Only (iii)
• B. Only (iv)
• C. Both (ii) and (iv)
• D. Both (iii) and (iv)

Answer 1

The correct option is D Both (iii) and (iv)

A reaction which undergoes breaking of bonds and formation of new bonds to form new products 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 heating of platinum at a high temperature involves oxidation reaction and new products are formed.