Write the balanced chemical equation for the following:

(a) Action of heat on manganese dioxide and concentrated hydrochloric acid.

(b) Zinc reacts with dilute hydrochloric acid to form zinc chloride.

Distinguish between the following as directed:

(a) Sodium sulphite solution and sodium sulphate solution. [using dilute H₂SO₄]

(b) Lead salt solution and zinc salt solution. [using NH₄OH solution in excess]

Select the right answer from the brackets and complete the statements:

In electrolysis of fused Alumina, the anode is made of (a) …………… [gas carbon/graphite] and the product formed at cathode is (b) …………… [oxygen/aluminium].

Study the diagram, which shows the Brown Ring Test and answer the questions given below:

(a) Which ion is determined by Brown Ring Test?

(b) Why is freshly prepared iron[II] sulphate used in the test?

(c) Name the substance Z.