Select the correct option for true or false statements:
${\mathbf{S}}_1:$ Dimethylsulphoxide (DMSO) is a good solvent for ${\mathrm{S}}_{\mathrm{N}}1$ reactions of alkyl halides.
${\mathrm{S}}_2: {\mathrm{H}}_2\mathrm{O}$ acts as ionising solvent for tertiary alkyl halides.
${\mathrm{S}}_3:$ The reactivity of $\mathrm{HX}$ for alcohols is $\mathrm{HI}>\mathrm{HBr}>\mathrm{HCl}$.
${\mathrm{S}}_4:$ Protonated alcohol $\left(\mathrm{R}-\stackrel{\oplus }{\mathrm{O}}{\mathrm{H}}_2\right)$ is less reactive than $\mathrm{ROH}$ for ${\mathrm{S}}_{\mathrm{N}}1$ reaction.