Carborundum is obtained when silica is heated at high temperature with

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 $(B)$.

Which of the following oxidation states are the most characteristic for lead and tin respectively?

Which of the following statements are correct?
$1.$ Charcoal can be obtained by heating wood in the absence of air.
$2.$ Charcoal is an impure form of graphite.
$3.$ Diamond is thermodynamically the most stable allotrope of carbon.
$4.$ Coke is used as an oxidising agent during the extraction of iron from its ores.

Identify the species,which does not exist?

Give the name of the basic structural unit of silicates and provide its examples.