Heating rubber with sulphur is known as

The answer is 3. vulcanization.

Heating rubber with sulphur is known as vulcanization. Vulcanization is a process that improves the properties of rubber, such as its strength, elasticity, and resistance to heat and chemicals. The sulphur molecules react with the rubber molecules to form cross-links between them. This creates a more durable and stable rubber product.

Galvanization is the process of coating metal with zinc to protect it from corrosion. Bessemerization is a process of removing impurities from iron ore to produce steel. Sulphonation is the process of adding sulphur to a molecule.

So, heating rubber with sulphur is known as vulcanization, not galvanization, bessemerization, or sulphonation.