(a) Describe an activity to show that metals are good conductors of electricity.(b) Account for the following:(i) Hydrogen gas is not evolved when a metal reacts with nitric acid. (ii) For storing sodium metal, it is kept immersed in kerosene. (iii) The reaction of iron (III) oxide with aluminium is used to join cracked iron part machines.

(a) Describe an activity to show that metals are good conductors of el

1.	(a) Describe an activity to show that metals are good conductors of electricity.(b) Account for the following:(i) Hydrogen gas is not evolved when a metal reacts with nitric acid. (ii) For storing sodium metal, it is kept immersed in kerosene. (iii) The reaction of iron (III) oxide with aluminium is used to join cracked iron part machines.
Answer» Solution : (a) Activity: (1) Set up an electric circuit as shown in the figure. (2) Place the metal to be tested in the circuit between terminals A and B as shown. (3) We find that the bulb glows. This shows that metals aregood conductors of electricity. (b) (i) This is because the hydrogen gas first evolved reacts with `HNO_3`to produce oxides of nitrogen. (ii) We cannot store it under WATER because sodium reacts with water to produce hydrogen gas. `2NA + 2H_2O to 2NaOH + H_2` (iii) `FeO_3 + 2AL to Al_2O_3 + 2Fe` + heat This is EXOTHERMIC REACTION. The molten iron is used to join cracked iron parts of machine.