Sulphurous anhydride is

Sulfurous anhydride, also known as sulfur dioxide (SO₂), is a colorless gas with a pungent odor. It is formed by the combustion of sulfur-containing materials, such as fossil fuels and industrial processes. Sulfurous anhydride is a common air pollutant and can contribute to acid rain formation. It is also used in various industrial applications, such as in the production of sulfuric acid, paper, and wine. Additionally, it is used as a preservative in dried fruits and meats, as well as in the food and beverage industry as a disinfectant and antioxidant. Sulfurous anhydride is a highly reactive gas that can form sulfurous acid when it reacts with water, and it can also react with other chemicals to form sulfites and sulfates.