AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
The chemical formula of hydrated copper sulphate is CuSO₄.5H₂O; five water molecules are present in one formula unit.
Source: Chapter 2, Section 2.4.4
The examiner expects both pieces of information: the correct formula CuSO₄.5H₂O and the number 5. Writing only the formula without stating "five water molecules" (or vice versa) will likely cost you the mark, as the question explicitly asks for both. Remember: the ".5H₂O" part represents the water of crystallisation — the fixed number of water molecules in one formula unit of the salt.