Which of the following oxides is amphoteric in character?

Match the items in Column $I$ with its main use listed in Column $II$.

Column $I$	Column $II$
$A$. Silica gel	$i$. Transistor
$B$. Silicon	$ii$. Ion-exchanger
$C$. Silicone	$iii$. Drying agent
$D$. Silicate	$iv$. Sealant

Which one of the following is present in the chain structure of silicates?

$Si_2O_7^{6-}$ anion is obtained when

Which of the following non-metals has half the atomicity of sulfur?

Consider the following route of reactions $R_2SiCl_2 + H_2O \to (A) \xrightarrow{\text{Polymerisation}} (B)$. Compound $(B)$ in the above reaction is: