Which of the following is the most popular oxoacid of sulfur?

Sulfuric acid

The correct answer is option 2.Sulfuric acid.

Among the options provided, the most popular oxoacid of sulfur is Sulfuric acid.

1. Sulfurous Acid \((H_2SO_3)\):

Sulfurous acid is a relatively weak acid and is less common compared to sulfuric acid. It is formed by dissolving sulfur dioxide \((SO_2)\) in water and is mainly used in various chemical processes and as a reducing agent.

2. Sulfuric Acid \((H_2SO_4)\):

Sulfuric acid is one of the most widely used and important industrial chemicals. It is extensively used in various industries for its strong acidic properties and versatile applications, including in the production of fertilizers, chemicals, detergents, batteries, and many other products. Sulfuric acid is also commonly used in laboratories and research settings.

3. Peroxodisulfuric Acid \((H_2S_2O_8)\):

Peroxodisulfuric acid, also known as persulfuric acid, is a strong oxidizing agent. It is used in various chemical reactions, including as a bleaching agent, as an oxidizer in organic synthesis, and in the preparation of other sulfur-containing compounds.

4. Pyrosulfuric Acid \((H_2S_2O_7)\):

Pyrosulfuric acid, also known as fuming sulfuric acid or oleum, is a powerful dehydrating agent. It is used in various industrial processes, such as in the production of detergents, dyes, explosives, and pharmaceuticals, as well as in the synthesis of other sulfuric acid derivatives.

While all of the provided oxoacids of sulfur have their uses, sulfuric acid (H2SO4) stands out as the most popular and widely used due to its extensive industrial applications and importance in various chemical processes.

Therefore, the correct option is: Sulfuric acid.