Why does distilled water not conduct electricity, whereas rain water does?

If a few drops of a concentrated acid accidentally spill over the hand of a student,what should be done?

What is formed when sulfur trioxide gas is absorbed in concentrated sulfuric acid?

What happens when a solution of an acid is mixed with a solution of a base in a test tube?
$(i)$ The temperature of the solution increases
$(ii)$ The temperature of the solution decreases
$(iii)$ The temperature of the solution remains the same
$(iv)$ Salt formation takes place

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?

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	$d.$ $pH = 12$