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.

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].

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]

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.