State on what special properties the use of each of these metals depends:

(a) aluminium, (b) zinc?

(a) Aluminium:

1. Being a strong, light and corrosion resistant metal, it is used in alloys.
2. Aluminium is light, it has high tensile strength, is resistant to corrosion, good conductor of heat, unaffected by organic acids and has attractive appearance. So it is used for making cooking utensils, in building and construction work.
3. Aluminium has a strong affinity for oxygen so it is used as a deoxidizer in the manufacture of steel.

(b) Zinc:

1. Zinc has a strong electropositive character, so it is used for coating iron and steel sheets to prevent them from rusting and this process is known as galvanization.
2. Due to strong electropositive nature, it forms Zn⁺²ions, so it is used to make dry cell containers which act as negative electrode.
3. Zinc act as a reducing agent for many organic reductions and these reductions are employed in manufacturing drugs, dyes.