Chemical formula of gypsum is _____.

The correct answer is option 1. \(CaSO_4.2H_2O\).

Gypsum is a naturally occurring mineral that has the chemical formula \(CaSO_4 \cdot 2H_2O\).

Gypsum is a hydrated calcium sulfate, meaning it contains water molecules within its crystal structure. The formula \(CaSO₄ \cdot 2H₂O\) indicates that each unit of gypsum consists of one calcium sulfate molecule (\(CaSO₄\)) combined with two water molecules (\(2H₂O\)). The water molecules are part of the crystal lattice and are not simply physically attached but are chemically bonded to the calcium sulfate.

Gypsum is widely used in construction and various industrial applications. When gypsum is heated, it loses its water content, and the resulting product is called "anhydrous calcium sulfate" or "dead-burned gypsum." The process of heating gypsum to remove water is known as calcination. Gypsum is also utilized in the production of plaster of Paris, cement, and as a soil conditioner in agriculture.