The constant number of water molecules present in one formula of a single unit of salt is known as:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. water of crystallisation.
The constant number of water molecules present in one formula unit of a salt is known as water of crystallization. These water molecules are chemically bound within the crystal lattice of the salt and play a crucial role in maintaining its crystalline structure. For example, in copper sulfate pentahydrate (CuSO₄·5H₂O), five water molecules are associated with each formula unit. When the salt is heated, the water of crystallization is lost, often changing the salt’s appearance and physical properties.