What are the other names for monoclinic sulfur and rhombic sulfur?

Excess of $PCl_{5}$ reacts with concentrated $H_{2}SO_{4}$ to give:

Among the elements of group $16$,which element exists in a metallic lattice in its monoatomic state and also exhibits two crystalline forms,$\alpha$ and $\beta$?

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:

When $H_2SO_4$ reacts with $PCl_5$,the obtained product$(s)$ is/are:

Identify the correct order of thermal stability of hydrides of $16$ group elements from the following.