Calculate the osmotic pressure of 0.1 molal solution of urea at 300K.

As per the question, the concentration is given in molal. For the calculation of osmotic pressure the concentration used in molar. To convert the given concentration in terms of molar the density of the solution should be given. If the given concentration is in molar, then the calculation will be as follows:
Given : 
       C = 0.1 M 
     R = 0.0821  L atm K^-1 mol^-1
     T = 300 K 

To find : 
 Osmotic pressure,$\pi$ = ? 

Solution :  
   ​osmotic pressure , $\pi =C\times R\times T$
  C = molal concentration of the solution  
  R = gas constant 
  T = temperature 

putting the values , we get 
   $\pi =0.1\times 0.0821\times 300$
   $\pi$ = 2.463 atm 

Osmotic pressure of the solution is 2.463 atm