A pale green crystalline salt X dissolves in water to give a pale green solution. The solution gives a deep blue precipitate with K3[Fe(CN)6] and a…

A pale green crystalline salt $\mathbf{X}$ dissolves in water to give a pale green solution. The solution gives a deep blue precipitate with $\mathrm{K_3[Fe(CN)_6]}$ and a white precipitate with $\mathrm{BaCl_2}$ that is insoluble in dilute $\mathrm{HCl}$. $\mathbf{X}$ contains seven molecules of water of crystallisation per formula unit. A sample of $2.78\ \mathrm{g}$ of $\mathbf{X}$ is strongly heated; the solid residue is a red-brown oxide and the evolved gases, in which $\mathrm{SO_2}$ and $\mathrm{SO_3}$ are formed in equal amounts, are passed into an excess of acidified aqueous $\mathrm{BaCl_2}$. Use molar masses (in $\mathrm{g\,mol^{-1}}$) $\mathrm{Fe}=55.85$, $\mathrm{S}=32.06$, $\mathrm{O}=16.0$, $\mathrm{H}=1.008$, $\mathrm{Ba}=137.33$. The masses of the solid residue and of the white precipitate formed in $\mathrm{BaCl_2}$ solution are respectively