Molarity of a 50 ml $H_{2}S{O}_4$ solution is 10M. If the density of the solution is 1.4g/cc calculate molality      

$m=\frac{massofsolute}{Gmwofsolue}\times \frac{1000}{massofsolvent}$

mass of $H_{2}S{O}_4$ $solute =$$10\times 98=980g$

mass of $H_{2}S{O}_4$solute in 50ml =

$\frac{980\times 50}{1000}=49gm$

Mass solution = $d\times v=1.4\times 50=70g$

$\therefore$ mass of solvent $=70-49=21gm$

$\therefore m=\frac{49}{98}\times \frac{1000}{21}=23.8m$