Hydrogen Halides HX

$\mathrm{HCl}\left(\mathrm{g}\right)$ can be prepared from $\mathrm{NaCl}$ and ${\mathrm{H}}_2{\mathrm{SO}}_4$ $\mathrm{while} \mathrm{HBr}\left(\mathrm{g}\right)$ and $\mathrm{HI}\left(\mathrm{g}\right)$
cannot be prepared in a similar way from $\mathrm{NaBr}$ and $\mathrm{NaI}$. Explain why is this so.

Give equations to show how the halogen acids $\mathrm{HF}, \mathrm{HCI}, \mathrm{HBr}$and $\mathrm{HI}$ may be prepared in aqueous solution. Why is $\mathrm{HF}$ a weak acid as compared to $\mathrm{HI}$  in water?