Concentrated $H_2SO_4$ reacts with $PCl_5$ to produce

Which of the following compounds undergoes hydrolysis easily?

Which of the following is the $CORRECT$ decreasing order of ionization enthalpies of the elements in Group $16$?

Given below are two statements:
Statement $I$: The boiling points of the following hydrides of group $16$ elements increase in the order: $H_2O < H_2S < H_2Se < H_2Te$.
Statement $II$: The boiling points of these hydrides increase with an increase in molar mass.
In the light of the above statements,choose the most appropriate answer from the options given below:

List the important sources of sulphur.

Write a note on the oxidation state of group-$16$ elements.