When silicate units are linked together,they form which type of structures?

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.

Which is an amphoteric oxide?

Which of the following is used for making optical instruments?

An inorganic compound $(A)$ made of the two most abundant elements in the Earth's crust is used in building construction. When $(A)$ reacts with carbon,it forms a poisonous gas $(B)$,which is a very stable diatomic molecule. Identify compounds $(A)$ and $(B)$.

In the following reaction,assign the state for the underlined atom in the product of complete hydrolysis at $R.T.$:
$\underline{S}F_4 + H_2O \longrightarrow H_2SO_3 + HF$