Thermodynamically most stable allotrope of carbon is

The basic building unit of all silicates is

Assertion : $SiF_6^{2-}$ is known but $SiCl_6^{2-}$ is not.
Reason : Size of fluorine is small and its lone pair of electrons interacts with $d-$orbitals of $Si$ strongly.

In which of the following sets are allotropes of carbon correctly matched with their uses?
$i$. graphite - crucibles
$ii$. activated charcoal - water filters
$iii$. carbon black - fuel
The correct answer is

Which of the allotropic forms of carbon is aromatic in nature?

The silicate having one monovalent corner oxygen atom in each $SiO_4$ tetrahedron unit is: