Consider the following statements:
$(a)$ $R_2SiO$ is the repeating unit of linear silicones.
$(b)$ $RSiCl_3$ on hydrolysis followed by dehydration gives linear silicones.
$(c)$ Silicones can be used as heat insulators.
$(d)$ Silica is soluble in $HF$.
The correct statement$(s)$ is/are:

For bleaching powder,which of the following statements is incorrect?

Identify the correct statements from the following.
$i$. Melting points and boiling points of group $13$ elements are much higher than those of corresponding group $14$ elements.
$ii$. $SiO$ only exists at high temperatures.
$iii$. $PbI_4$ does not exist.
$iv$. Buckminster fullerene contains twelve $6$-membered carbon rings and twenty $5$-membered carbon rings.

Pyrosilicate ion is

Explain fullerenes.

$CO + NaOH \to $