(i) conc. `HNO_(3)` reacts with aluminium to form aluminium oxide `(Al_(2)O_(3))` which forms a protective coating inside the container. The metal becomes passive and does not react with the acid any more Therefore, the acid can be safely stroed in aluminium container.
(ii) Graphie is used as lubricant becaue of its soft and gressy nature. this is probably due to the presence of layers in the arangement of carbon atoms is graphite.
(iii) Diamond is used as an abraisve because of its extremely hard nature (hardest substance known). Actually, the carbon atoms in diamond are very closely packed. this is responsible. for the harddness of diamond.
(iv) Alloys of aluminium: Manalium and Duralumin both of which contain about 95% of the metal are used for making aircraft body. Actually, both of them are light. tough and quite resistant to currosion. Therefore, they are used in making bodies of air crafts.
(v) Althoughthe metal as such is not affected by water, but when kept overnight, it may be slowly affected by moisture in the presence of oxygen (air).
`2Al(s)+O_(2)(g)+H_(2)O(l)rarrAl_(2)O_(3)(s)+H_(2)(g)`
(vi) The metal is not affected by air and moisture (resistat to corrosion) and also because of its good conductivity. it is used to make tramission cables.
