1 markMCQSection A

The chemical formula for plaster of Paris is:

Acids, Bases and Salts

Plaster of Paris

Options

(0)

\mathrm{CaSO_4 \cdot 2H_2O}

(1)

\mathrm{CaSO_4 \cdot H_2O}

(2)

\mathrm{CaSO_4 \cdot \frac{1}{2}H_2O}

(3)

\mathrm{2CaSO_4 \cdot H_2O}

Official Answer

The correct option is C.

Plaster of Pariscalcium sulphate hemihydrateCaSO4.1/2H2O

Hint

Plaster of Paris is a hemihydrate of calcium sulphate, meaning half a water molecule is associated with each formula unit of calcium sulphate.

Quick Oral Answer

The chemical formula of Plaster of Paris is $CaSO_4 \cdot \frac{1}{2}H_2O$ .

Plaster of Paris is chemically known as calcium sulphate hemihydrate. Its chemical formula is $CaSO_4 \cdot \frac{1}{2}H_2O$ .

Option A ( $CaSO_4 \cdot 2H_2O$ ) represents Gypsum, which is the precursor heated to make Plaster of Paris.
Options B and D are incorrect chemical representations of the hemihydrate form.

1Confusing the formula of Plaster of Paris ( $CaSO_4 \cdot \frac{1}{2}H_2O$ ) with Gypsum ( $CaSO_4 \cdot 2H_2O$ ).

Plaster of Paris got its name because it was historically prepared by heating abundant deposits of gypsum found near Paris, France.

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This question carries 1 mark in the CBSE Class 10 Science 2020 examination.

This question is from the chapter "Acids, Bases and Salts" in the CBSE Class 10 Science syllabus.

This question covers the topic "Plaster of Paris" from CBSE Class 10 Science.

This is a MCQ question from Section A in the CBSE Class 10 Science 2020 paper.