Aluminium is used for making cooking utensils. Which of the following properties of aluminium are responsible for the same?
$(i)$ Good thermal conductivity
$(ii)$ Good electrical conductivity
$(iii)$ Ductility
$(iv)$ High melting point

Which of the following gases is combustible?

Which metal oxide dissolves in water to form an alkali?

$(a)$ 'Sodium is a highly reactive metal and it cannot be obtained from its oxide by heating with carbon'. Give reason.
$(b)$ How can sodium be obtained from sodium chloride?

A non-metal $A$, which is the largest constituent of air, when heated with $H_2$ in a $1 : 3$ ratio in the presence of a catalyst $(Fe)$, gives a gas $B$. On heating with $O_2$, it gives an oxide $C$. If this oxide is passed into water in the presence of air, it gives an acid $D$, which acts as a strong oxidising agent.
$(a)$ Identify $A$, $B$, $C$, and $D$.
$(b)$ To which group of the periodic table does this non-metal belong?

Which gas is highly soluble in water?