Calcium sulphate dihydrate is commonly known as ________.

gypsum

The correct answer is option 1. gypsum.

Calcium sulfate dihydrate, commonly known as gypsum, is a mineral composed of calcium sulfate with the chemical formula \(CaSO_4·2H_2O\).

Gypsum is composed of calcium sulfate combined with two molecules of water (di meaning two, hydrate meaning water). Its chemical formula, \(CaSO_4·2H_2O\), reflects this composition. The presence of water molecules makes gypsum a hydrated mineral.

Gypsum occurs naturally in various forms, including as transparent crystals, fibrous masses, and granular masses. It is often found in sedimentary rock deposits and is commonly associated with evaporite mineral deposits formed by the evaporation of saline water.

In summary, gypsum, or calcium sulfate dihydrate, is a versatile mineral with important uses in construction, agriculture, industry, and art. Its abundance, stability, and beneficial properties make it a valuable resource for various practical applications.