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 $\beta$?

The most efficient agent for the absorption of $SO_3$ is

Among the hydrides of group $16$ elements, the hydride $X$ has the lowest boiling point and the hydride $Y$ has the highest boiling point. $X$ and $Y$ respectively are:

$A$ solution of $CrO_5$ in amyl alcohol has a $....$ colour.

It is possible to obtain oxygen from air by fractional distillation because

Given below are two statements: Statement $I$: The covalency of oxygen is generally two but it can exceed up to four. The oxidation state of oxygen in $SO_2$ is $-2$ and in $OF_2$ it is $+2$. Statement $II$: The anomalous behaviour of oxygen when compared to the other elements of group $16$ is due to its small size and high electronegativity. In the light of the above statements, choose the correct answer from the options given below.