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

Number of moles of Urea, $n=0.1\text{gram}\text{mol}$

Weight of solvent,${\text{W}}_{\text{solvent}}=100\text{ g}$

  $1000\text{g}=1\text{kg}$  

 $100\text{g}=\frac{1\text{kg}}{1000\text{g}}\times 100\text{g}\text{=0}\text{.1}\text{kg}$

From molality equation,

       $m=\frac{\text{n}}{\text{W in kg}}$

Explanation:

Molality (m) measures the concentration of a solute in a solution in moles of solute per kilogram of solvent. 

Mole formula is:

Molality (m) = Number of moles of solute) / Mass of solvent in kilograms

Given:

• Number of moles of urea (solute): 0.1 mol
• Mass of water (solvent): 100 g = 0.1 kg

Applying the values:

Therefore, the molality of the solution is 1 mol/kg.