HINT: Group ${16}^{\mathrm{th}}$ elements are called chalcogen.

Explanation:

1.) H₂SO₄ is used in storage batteries. Battery acid is sulfuric acid that has been diluted with water to attain a 38% concentration level. 

The sulphuric acid is used as an electrolyte in lead-acid batteries. During the discharge of lead-acid batteries, the lead sulphate is formed on both the electrodes because of the reaction with sulphuric acid.

When the battery charges, lead sulphate gets converted to lead and lead oxide by releasing the sulphuric acid into the electrolyte.

2.) CCl₃NO₂ (Chloropicrin) is known as tear gas. Chloropicrin (PS) is an irritant with characteristics of a tear gas. Chloropicrin (PS) has an intensely irritating odor.

3.) Cl₂ has the highest electron gain enthalpy. This is because the interelectronic repulsions in chlorine are weaker than in F due to bigger size of chlorine.

4.) Sulphur is a member of chalcogen i.e., ore-producing elements