Give reasons
Diamond is used as an abrasive.

Explanation

a.Aluminium reacts with conc.`HNO_(3)` to form a very fine layer of aluminium oxide, `Al_(2)O_(3)`, on its surface. This renders aluminium passive and protects it from further action.
`2Al_((s))+underset("conc.")(6HNO_(3))tounderset("Alumina")(Al_(2)O_(3(s)))+6NO_(2(g))+3H_(2)O_((l))`
Since alumiuium has become passive, it can be used to transport conc.`HNO_(3)`.
b. `NaOH` reacts with `Al` to evolve hydrogen gas. The presence of the gas thus produced can be used to open clogged drains.
`2Al_((s))+2NaOH_((aq))+2H_(2)O_((l))to 2NaAlO_(2(aq))+3H_(2)uarr_((g))`
c. Graphite has a layer-like structure is which different layers are stacked on one another and held together by weak van der Walls forces of attraction.These weak forces can be easily overcome.Thus,graphite acts as a lubricant.
d. Diamond is very hard and hence can be used as an abrasive.
e. Alumina alloys are light, tough and resistant to corrosion and hence are used to make aircraft body.
f. Aluminium reacts with water and dissolved `O_(2)` to form a thin layer of `Al_(2)O_(3)`.
`2Al_((s))+O_(2(g)+H_(2)O_((l))to Al_(2)O_(3(s))+H_(2)uarr_((g))`
A very small amount of `Al_(2)O_(3)` may dissolve to give a few ppm of `Al^(3+)` ions in the solution. Since `Al^(3+)` ions are carcinogenic in nature and hence injurious to health. For the reason,drinking water should not be stored in aluminium utensils overnight.
g. On weight-to-weight basis,aluminium conducts twice as copper,therefore, it is used in transmission cables.