Which of the following is not a mineral acid?

The compound which is used as an oxidising agent in many chemical industries is:

State whether the following statement is true or false:
When the $pH$ of rainwater is more than $5.6,$ it is called acid rain.

If $[H_3O^+] = 10^{-6} \ M$ in an aqueous solution,what is the $pH$ of the solution?

Give reasons for the following:
$(i)$ Why is it recommended that acid should be added to water and not water to acid?
$(ii)$ Why do compounds like alcohol and glucose not show acidic behavior even though they contain hydrogen?

Which one of the following can be used as an acid-base indicator by a visually impaired student?