Q1. [1] § 2.1 UNDERSTANDING THE CHEMICAL PROPERTIES OF ACIDS AND BASES § 2.2 WHAT DO ALL ACIDS AND ALL BASES HAVE IN COMMON? § 2.4 MORE ABOUT SALTS
A common feature observed in the crystals of washing soda, copper sulphate, gypsum and ferrous sulphate is that all
- A exhibit basic nature
- B exhibit acidic nature
- C have fixed number of molecules of water of crystallisation in one formula unit of these salts.
- D are coloured
Previously asked in CBSE board exam
2025 31/5/1 Q3
Generated by claude-sonnet-4-6 · 2026-06-15 06:45 · grounding rag
Model Answer
The correct answer is C — they have a fixed number of molecules of water of crystallisation in one formula unit of these salts.
Explanation
"Water of crystallisation" means the fixed number of water molecules chemically bonded in one formula unit of a salt crystal (e.g., Na₂CO₃·10H₂O, CuSO₄·5H₂O, CaSO₄·2H₂O, FeSO₄·7H₂O). This is the one property common to all four salts. They are not all coloured (washing soda is white), nor are they all acidic or basic — they are salts, which can be neutral, acidic, or basic depending on the parent acid/base.
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.