Question

Why can metals high up in the reactivity series not be obtained by reduction of their oxides by carbon ?

The metals which are found in both free state as well as combined state are :

Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded.

Three metal samples of magnesium, aluminium and iron were taken and rubbed with sand paper. These samples were then put separately in test tubes containing dilute hydrochloric acid. Thermometers were also suspended in each test tube so that their bulbs dipped in the acid. The rate of formation of bubbles was observed. The above activity was repeated with dilute nitric acid and the observations were recorded. Answer the following questions :

Assertion (A) : A piece of Zinc metal gets reddish brown coating when kept in copper sulphate solution for some time. Reason (R) : Copper is more reactive metal than Zinc.