Assertion: $Ozone$ is a powerful oxidising agent in comparison to $O_2$.
Reason: $Ozone$ is diamagnetic but $O_2$ is paramagnetic.

Among the following allotropic forms of sulphur,the number of allotropic forms,which will show paramagnetism is ..... .
$(A)$ $\alpha$-sulphur
$(B)$ $\beta$-sulphur
$(C)$ $S_2$-form

Given below are two statements $:$
Statement $I : H_2Se$ is more acidic than $H_2Te$.
Statement $II : H_2Se$ has higher bond enthalpy for dissociation than $H_2Te$.
In the light of the above statements,choose the correct answer from the options given below.

Which element from the following does $NOT$ belong to the chalcogen family?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$ : Both rhombic and monoclinic sulphur exist as $S_8$ while oxygen exists as $O_2$.
Reason $(R)$ : Oxygen forms $p \pi-p \pi$ multiple bonds with itself and other elements having small size and high electronegativity like $C, N$,which is not possible for sulphur.
In the light of the above statements,choose the most appropriate answer from the options given below:

The thermal stability of the hydrides of group-$16$ elements follows the order: