When a $pH$ paper is dipped in an aqueous solution,it turns blue. What is the approximate $pH$ value of that solution?

$(a)$ Give the chemical names of acids present in:
$(i)$ ants
$(ii)$ lemon
$(iii)$ milk
$(iv)$ tomato

If the concentration of hydronium ions in an aqueous solution is $[H_3O^+] = 10^{-5} \; M$,what is the $pOH$ of the solution?

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

Write the balanced chemical equations for the following reactions:
$(a)$ Chlorine is passed over dry slaked lime.
$(b)$ Sodium bicarbonate reacts with dilute hydrochloric acid.
$(c)$ Sodium bicarbonate is heated.

The $.........$ of the molar concentration of $[H_3O^+]$ in an acidic aqueous solution is called the $pH$ of that solution.