$\Lambda_{ m }^{\infty}\left( BaSO _{4}\right)=\lambda_{ m }^{\infty}\left( Ba ^{2+}\right)+\lambda_{ m }^{\infty}\left( SO _{4}^{2-}\right)$
$\Lambda_{ m }^{\infty}\left( BaSO _{4}\right)=\Lambda_{ m }^{\infty}\left( BaCl _{2}\right)+\Lambda_{ m }^{\infty}\left( H _{2} SO _{4}\right)-2\Lambda_{ m }^{\infty}\left( HCl\right)$
$=280+860-2(426)$
$=288 \,Scm ^{2} mol ^{-1}$
$Cu ( s )+ Sn ^{2+}( aq ) \rightarrow Cu ^{2+}( aq )+ Sn ( s )$
$\left( E _{ Sn ^{2+} \mid Sn }^{0}=-0.16\, V , E _{ Cu ^{2+} \mid Cu }^{0}=0.34\, V \right.$ Take $F=96500\, C\, mol ^{-1}$ )