If $1$ mole of salt is dissolved in $2$ liters of salt solution,what is the concentration of the solution (in $;M$)?

Give reasons for the following:
$(i)$ Why is it recommended that acid should be added to water and not water to acid?
$(ii)$ Why do compounds like alcohol and glucose not show acidic behavior even though they contain hydrogen?

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?

What is the molarity of a solution prepared by dissolving $8 \ g$ of $NaOH$ in water to make a total volume of $100 \ mL$ (in $M$)?

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

$10 \,mL$ of a solution of $NaOH$ is found to be completely neutralized by $8 \,mL$ of a given solution of $HCl$. If we take $20 \,mL$ of the same solution of $NaOH$,the amount of $HCl$ solution (the same solution as before) required to neutralize it will be ...... $mL$.