What is formed when $H_2S$ reacts with $O_2$?

Sulphur trioxide can be obtained by which of the following reactions?

Among Group $16$ elements,which one does $NOT$ show $-2$ oxidation state?

Which of the following oxides of sulfur contains a sulfur-sulfur $(S-S)$ bond?

$H_2S$ is more acidic than $H_2O$,due to

Indicate the products $(X)$ and $(Y)$ in the following reactions:
$Na_{2}S + nS (n=1-8) \rightarrow (X)$
$Na_{2}SO_{3} + S \rightarrow (Y)$