White anhydrous copper sulphate turns blue in the presence of water. In which test is this useful?
Answer and explanation
Correct answer: Test for the presence of water
Anhydrous copper sulphate is white because it lacks water of crystallisation. When water is present, it becomes hydrated copper sulphate, CuSO4·5H2O, which is blue. This clear colour change makes it a useful qualitative test for water or moisture. Thus option A is correct; oxygen, hydrogen and chlorine require different chemical tests and do not cause this characteristic change.
Frequently asked questions
What is the correct answer to this question?
Test for the presence of water
Why is this the correct answer?
Anhydrous copper sulphate is white because it lacks water of crystallisation. When water is present, it becomes hydrated copper sulphate, CuSO4·5H2O, which is blue. This clear colour change makes it a useful qualitative test for water or moisture. Thus option A is correct; oxygen, hydrogen and chlorine require different chemical tests and do not cause this characteristic change.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
