In which of the following oxyacids is an $O$ atom $NOT$ present between two central atoms?

Give the uses of silicones.

Identify the correct statements among the following:
$a$) $C_{60}$ molecule has $12$ five-membered rings and $20$ six-membered rings.
$b$) $H_2CO_3 / HCO_3^-$ buffer system helps to maintain $pH$ of blood between $7.26$ and $7.42$.
$c$) Graphite is used as a dry lubricant in machines running at high temperatures.

The tendency of catenation in group-$14$ elements follows the order:

Which of the following tetrahalides does not exist?

Explain the following reactions:
$(a)$ Silicon is heated with methyl chloride at high temperature in the presence of copper.
$(b)$ Silicon dioxide is treated with hydrogen fluoride.
$(c)$ $CO$ is heated with $ZnO$.
$(d)$ Hydrated alumina is treated with aqueous $NaOH$ solution.