An aqueous solution of copper sulphate turns colourless on electrolysis. Which of the following could be the electrodes?

P. anode: copper; cathode: copper

Q. anode: platinum; cathode: copper

R. anode: copper; cathode: platinum

1. only P
2. only Q
3. only R
4. both Q and R

A compound P is heated in a test tube with sodium hydroxide solution. A red litmus paper held at the mouth of the test tube turns blue. Which of the following could compound P be?

1. zinc sulphate
2. copper sulphate
3. ferrous sulphate
4. ammonium sulphate

The equation below shows the reaction between element 'X' and dilute sulphuric acid.

X(s) + H₂SO₄ (aq.) ⟶ XSO₄ (aq.) + H₂ (g)

Which particles are responsible for conducting electricity in dilute sulphuric acid and compound XSO₄?

1. Electrons
2. Only positive ions
3. Only negative ions
4. Both positive and negative ions

Assertion (A): Dry hydrogen chloride gas is collected by the upward displacement of air.

Reason (R): Hydrogen chloride gas is lighter than air.

1. Both A and R are true and R is the correct explanation of A
2. Both A and R are true but R is not the correct explanation of A
3. A is true but R is false
4. A is false but R is true