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

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

Which of the following cannot be used as an antacid for the treatment of acidity?

$15 \, mL$ of water and $10 \, mL$ of sulphuric acid are to be mixed in a beaker.
$(i)$ State the method that should be followed with reason.
$(ii)$ What is this process called?

List-$I$ contains aqueous solutions,and List-$II$ contains their corresponding $pH$ values. Which of the following matches is correct?

List-$I$	List-$II$
$1.$ Vinegar solution	$a.$ $pH = 7.4$
$2.$ Blood	$b.$ $pH = 2.5$
$3.$ Washing soda solution	$c.$ $pH = 7.0$
$4.$ Pure water	$d.$ $pH = 12$

Which of the following statements is not correct?