Give reasons for the following :
(a) Aluminium wire is used in transmission cables.
(b) Aluminium utensils should not be used to strore drinking water for long time.
( c) A mixture of `Al` pieces and `NaOH` is used to open the drain.
(d) Aluminium alloys are used to make aircraft bodies.

Explanation

(a) Aluminium wire is used in transmission cables because of the following reasons :
(i) It is a good conductor of electricity.
(ii) It is not affected by atmosphere.
(b) Aluminium is slowly attacked by water and dissolved `O_(2)` to form `Al_(2) O_(3)` on the surface. A very small amount of `Al_(2) O_(3)` may get dissolved to form `Al^(3+)` ions. Sine `Al^(3+)` ions are injurious to health, drinking water should not be stored in aluminium vessels.
( c) `NaOH` reacts with `Al` to evolve hydrogen.
`2 Al + 2 NaOH rarr 2NaAlO_(2) + H_(2) uarr`
This evolved hydrogen helps in opening the drain.
(d) Aluminium alloys are light, tough and corrosion reisstant. Hence, aluminium alloys are used to make aircraft bodies.