The reagent(s) used for softening the temporary hardness of water is(are)

Softening the temporary hardness of water means conversion of bicarbonate into calcium carbonate (precipitation) $$ \begin{gathered} \mathrm{Ca}\left(\mathrm{HCO}_3\right)_2+\mathrm{Ca}(\mathrm{OH})_2 \longrightarrow \\ 2 \mathrm{CaCO}_3 \downarrow+2 \mathrm{H}_2 \mathrm{O} \\ \mathrm{Ca}\left(\mathrm{HCO}_3\right)_2+\mathrm{Na}_2 \mathrm{CO}_3 \longrightarrow \\ \mathrm{CaCO}_3 \downarrow+2 \mathrm{NaHCO}_3 \end{gathered} $$ Even $\mathrm{NaOCl}$ can be used, as in aqueous medium $\overline{\mathrm{O}} \mathrm{Cl}$ gets hydrolysed and makes solution alkaline enough to cause precipitation of $\mathrm{CaCO}_3$. $$ \begin{aligned} \mathrm{NaOCl}+\mathrm{H}_2 \mathrm{O} & \rightleftharpoons \mathrm{HOCl}+\mathrm{NaOH} \\ \mathrm{OH}^{-}+\mathrm{HCO}_3^{-} & \longrightarrow \mathrm{CO}_3^{2-}+\mathrm{H}_2 \mathrm{O} \end{aligned} $$ Representative elements (Hydrogen and its compounds) Conceptual II