Which of the following elements forms a molecule consisting of eight of its own atoms?

$A$ compound $A$ is used in paints instead of salts of lead. Compound $A$ is obtained when a white compound $B$ is strongly heated. The compound $B$ is insoluble in water but dissolves in $NaOH$ solution,forming a solution of compound $C$. The compound $A$ on heating with coke gives a volatile metal $D$ and a gas $E$ which burns with a blue flame. Identify the possible species $D$ and $C$ respectively.

Manmade silicate is $........$
$........$ is used to convert alcohols directly into gasoline. Give the use of hydrated zeolites.

In the following reaction,identify the nature of the product formed by the complete hydrolysis of the underlined atom at $R.T$:
$H_6\underline{Si}_2O_7 + H_2O \longrightarrow H_4SiO_4$

Write the general and empirical formula of silicone.

How is dry ice produced? Mention its uses.