As the concentration of $[H_{3}O^{+}]$ ions increases in an acidic aqueous solution,what happens to the nature of the solution?

Dry $HCl$ gas does not change the colour of dry blue litmus. Give reason.

Which of the following is a mineral acid?

Which of the following is a weak acid?

Equal lengths of magnesium ribbon are taken in two test tubes $A$ and $B$. $H_{2}SO_{4}$ is added to test tube $A$ and $H_{2}CO_{3}$ in test tube $B$ in equal amounts.
$(a)$ Identify the test tube showing vigorous reaction.
$(b)$ Give reason to support your answer.
$(c)$ Name the gas liberated in both the test tubes. How will you prove its liberation?

How does the acidity of an acidic aqueous solution change as the concentration of $[H_{3}O^{+}]$ decreases?