$500 \ ml$ aqueous solution is prepared by dissolving $2$ moles of $HCl$ in water. What will be the molarity of this solution (in $M$)?

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

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	$d.$ $pH = 12$

Name the gas evolved when dilute $HCl$ reacts with sodium hydrogen carbonate. How is it recognized?

The $pH$ of a water sample collected from a river was found to be acidic in the range of $3.5-4.5$. On the banks of the river were several factories that were discharging effluents into the river. The effluents of which one of the following factories is the most likely cause for lowering the $pH$ of river water?

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