Which one of the following metals is found in ‘Plaster of Paris’ ?

Plaster of Paris is chemically identified as calcium sulfate hemihydrate, represented by the formula CaSO4·1/2H2O [1][t1]. It is produced by heating gypsum, which is calcium sulfate dihydrate (CaSO4·2H2O), until it loses a portion of its water of crystallization [c1][t4]. The primary metallic element present in this compound is Calcium (Ca), which belongs to the alkaline earth metal group [t2]. When Plaster of Paris is mixed with water, it undergoes an exothermic reaction to re-form gypsum, creating a hard solid mass used extensively in medical settings for supporting fractured bones and in industrial applications like mold making [c1][t6]. Other metals like magnesium, potassium, and sodium form different sulfate salts (e.g., magnesium sulfate or sodium sulfate) but are not the constituent metals of Plaster of Paris [c3][t5].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Plaster of Paris > p. 33