STD 11 - 3. Classification of elements and periodicity in properties — NEET STD 11 Science — Question

$C{l_2} + 2B{r^ - }\left( {aq} \right) \to 2C{l^ - }\left( {aq} \right) + B{r_2}$

$Br_2$ gas thus formed is dissolved into solution of $Na_2CO_3$ and then pure $Br_2$ is obtained by treatment of the solution with