The equation for the reaction of strontium hydroxide with hydrochloric acid is shown below.

$\mathrm{Sr}{\left(\mathrm{OH}\right)}_2+2\mathrm{HCl}\to {\mathrm{SrCl}}_2+2{\mathrm{H}}_2\mathrm{O}$

$25.0 {\mathrm{cm}}^3$ of a solution of strontium hydroxide was exactly neutralised by $15.00 {\mathrm{cm}}^3$ of $0.100 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid. Calculate the concentration, in $\mathrm{mol} {\mathrm{dm}}^{-3}$, of the strontium hydroxide solution.

$20.0 {\mathrm{cm}}^3$ of a $0.400 \mathrm{mol} {\mathrm{dm}}^{-3}$ solution of sodium hydroxide was exactly neutralised by $25.25 {\mathrm{cm}}^3$ of sulphuric acid. Calculate the concentration, in $\mathrm{mol} {\mathrm{dm}}^{-3}$, of the sulphuric acid. The equation for the reaction is: 

${\mathrm{H}}_2{\mathrm{SO}}_4+2\mathrm{NaOH}\to {\mathrm{Na}}_2{\mathrm{SO}}_4+2{\mathrm{H}}_2\mathrm{O}$.

$20.0 {\mathrm{cm}}^3$ of a metal hydroxide of concentration $0.0600 \mathrm{mol} {\mathrm{dm}}^{-3}$ was titrated with $0.100 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid. It required $24.00 {\mathrm{cm}}^3$ of the hydrochloric acid to exactly neutralise the metal hydroxide. Calculate the number of moles of metal hydroxide used.

$20.0 {\mathrm{cm}}^3$ of a metal hydroxide of concentration $0.0600 \mathrm{mol} {\mathrm{dm}}^{-3}$ was titrated with $0.100 \mathrm{mol} {\mathrm{dm}}^{-3}$ hydrochloric acid. It required $24.00 {\mathrm{cm}}^3$ of the hydrochloric acid to exactly neutralise the metal hydroxide. Calculate the number of moles of hydrochloric acid used.

$0.4 \mathrm{moles}$ of aluminium sulphate, ${\mathrm{Al}}_2{\left({\mathrm{SO}}_4\right)}_3$, are dissolved in water and the volume of the solution was made up to $500 {\mathrm{cm}}^3$. Which one of these statements is correct?

A. The solution contains a total of $2$ moles of ions.

B. The concentration of aluminium ions is $0.8 \mathrm{mol} {\mathrm{dm}}^{-3}$.

C. The concentration of sulphate ions in solution is $1.2 \mathrm{mol} {\mathrm{dm}}^{-3}$.

D. The solution contains a total of $4$ moles of ions.

$50 {\mathrm{cm}}^3$ of a gaseous hydride of phosphorus, ${\mathrm{PH}}_{\mathrm{n}}$ reacts with exactly $150 {\mathrm{cm}}^3$ of chlorine, ${\mathrm{Cl}}_2$, to form liquid phosphorous trichloride and $150 {\mathrm{cm}}^3$ of hydrogen chloride gas, $\mathrm{HCl}$. How many moles of chlorine react with $1$ mole of the gaseous hydride?