Which of the following properties correctly explain $SiO_2$?

Rationalise the given statements and give chemical reactions:
$1$. Lead $(II)$ chloride reacts with $Cl_2$ to give $PbCl_4$.
$2$. Lead $(IV)$ chloride is highly unstable towards heat.
$3$. Lead is known not to form an iodide,$PbI_4$.

The sides of a matchbox have a coating of:

Deep sea divers use a mixture of ....... for respiration.

Oxygen gas is not produced from the following decomposition reaction:

Nitrolim is