Which one of the following is a conductor in the solid state ?
( a ) sodium chloride
(b) diamond
( c) graphite
(d) sulphur

Which one of the following exists as covalent crystals in the solid state?

Which one of the following forms a molecular solid when solidified?

Which of the following shows only one oxidation state?

There are four major causes of accelerated rates of species extinction, which are collectively called as 'the evil quartet'. Which one of the following is not included in 'the evil quartet' ? (a) Over exploitation (b) Pollution (c) Co-extinctions (d) Alien species invasions