In the presence of which catalyst is vegetable ghee prepared from vegetable oil?

Name two metals which react with dilute $HNO_{3}$ to evolve $H_{2}$ gas.

Non-metals form two types of oxides. Choose these two types from the following oxides:
$SO_2, NO_2, CO, H_2O, N_2O$

Galvanisation is a method of protecting:

Give reasons for the following:
$(i)$ Alloys are used in electrical heating devices rather than pure metals.
$(ii)$ Gold ornaments look new even after several years of use.
$(iii)$ An iron grill should be painted frequently.

An element $A$ reacts with water to form a compound $B$ which is used in white washing. The compound $B$ on heating forms an oxide $C$ which on treatment with water gives back $B$. Identify $A$,$B$ and $C$ and give the reactions involved.