The paste of a white material in water is used to maintain a fractured bone fixed in place. The white material used is called

The white material used to maintain a fractured bone in place is Plaster of Paris (POP). Chemically known as calcium sulfate hemihydrate, it is a white powder that, when mixed with water, undergoes a chemical reaction to revert into gypsum (calcium sulfate dihydrate) [1]. This process results in a hard, solid mass that provides the necessary support and immobilization for broken bones [1]. Historically, POP has been a staple in orthopaedics for preventing deformity and stabilizing fractures due to its cost-effectiveness and ease of application [1]. While other materials like lime powder (calcium oxide) react vigorously with water to form slaked lime, they are used in construction rather than medical casting [2]. Bleaching powder and zinc oxide serve different chemical and medicinal purposes and do not possess the setting properties required for orthopaedic casts [2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > Plaster of Paris > p. 33
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 1: Chemical Reactions and Equations > Figure 1.3 > p. 6