What is the chemical formula of the substance which doctors use as plaster for supporting fractured bones in the right position?

CaSO₄.\(\frac{1}{2}\)H₂O

The correct answer is option 4. CaSO₄.\(\frac{1}{2}\)H₂O

Plaster of Paris (POP): Calcium sulphate hemihydrate (CaSO₄.\(\frac{1}{2}\)H₂O) 

POP is the substance that doctors use as plaster for supporting fractured bones in the right position.

Plaster of Paris is a white powder and on mixing with water, it changes to gypsum once again giving a hard solid mass.