Question

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.

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.

Assertion (A) : Different metals have different reactivities with water and dilute acids. Reason (R) : Extraction of a metal from its ore depends on its position in the reactivity series.

Give an example of a metal which (i) is a liquid at room temperature. (ii) can be easily cut with a knife. (iii) is the best conductor of heat. (iv) is a poor conductor of heat.