0.1 gram mole of urea is dissolved in 100g. of water. The molality of the solution is

Given, weight of the solvent = 100g = 0.1kg

Moles of urea(solute) = 0.1moles 

$\mathrm{Molality} =\frac{ \mathrm{moles} \mathrm{of} \mathrm{solute} }{ \mathrm{massof} \mathrm{solvent} \mathrm{in} \mathrm{kg}}$$=\frac{0.1}{0.1}=1\mathrm{molal}$

Therefore, option A is correct.