Which of the elements of group $16$ has the maximum tendency of catenation?

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:

The key step in the manufacturing of $H_2SO_4$ by contact process is

Which of the following dinegative anions is quite common?

The highest catenation ability is shown by

Which of the following is not correct?