The amorphous form of silica is

In $P_4O_{10}$,the number of oxygen atoms attached to each phosphorus atom is

Identify $B$ in the following reaction:
$H_4SiO_4$ $\xrightarrow[{-H_2O}]{1000^{\circ}C} A$ $\xrightarrow[\Delta]{Carbon} B + CO$

The main reason that $SiCl_{4}$ is easily hydrolysed as compared to $CCl_{4}$ is that

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T.$:
$\underline{P}OCl_3 + H_2O \longrightarrow H_3PO_4 + HCl$

Which of the following substances is used in smoke screens?