Which ions are responsible for the chemical properties of bases in their aqueous solution?

If the $pH$ of an aqueous solution is $6$,then its $pOH$ is:

Dry hydrogen chloride gas does not turn blue litmus red whereas hydrochloric acid does. Give one reason.

Which of the following phenomena occur when a small amount of acid is added to water?

Tooth enamel is the hardest substance in our body. Name the compound of which it is made up. At what $pH$ of the mouth does it get corroded? State the role of bacteria present in the mouth. Suggest a method to prevent tooth decay.

$(a)$ If we take hydrochloric acid and acetic acid of the same concentration,which one will produce a lower $H^{+}$ ion concentration? Out of the two,which one is a weak acid?
$(b)$ If someone is suffering from acidity,which of the following would you suggest to cure it: vinegar,orange juice,or baking soda solution? Give a reason for your answer.