The osmotic pressure of a solution is the pressure required to prevent the flow of solvent into the solution through a semi-permeable membrane. It is directly proportional to the concentration of solute particles in the solution.

To determine the osmotic pressure of the solution obtained by mixing a 200 cm3 2% solution of urea with a 200 cm3 3.42% solution of sucrose at 20 degrees Celsius, we need to calculate the concentration of solute particles in the final solution.

1. Calculate the amount of urea in the 2% solution:
- 2% solution means there are 2 g of urea in 100 cm3 of solution.
- So, in 200 cm3 of solution, there will be 2 g * (200 cm3 / 100 cm3) = 4 g of urea.

2. Calculate the amount of sucrose in the 3.42% solution:
- 3.42% solution means there are 3.42 g of sucrose in 100 cm3 of solution.
- So, in 200 cm3 of solution, there will be 3.42 g * (200 cm3 / 100 cm3) = 6.84 g of sucrose.

3. Calculate the total amount of solute in the final solution:
- The final solution is obtained by mixing the 200 cm3 of the urea solution and the 200 cm3 of the sucrose solution.
- So, the total amount of solute in the final solution is 4 g + 6.84 g = 10.84 g.

4. Calculate the concentration of solute particles in the final solution:
- The total volume of the final solution is 200 cm3 + 200 cm3 = 400 cm3.
- The concentration of solute particles is given by (amount of solute / total volume of solution) * 100.
- So, the concentration of solute particles in the final solution is (10.84 g / 400 cm3) * 100 = 2.71%.

5. Calculate the osmotic pressure of the final solution:
- Osmotic pressure can be calculated using the formula: π = nRT/V
- π is the osmotic pressure
- n is the number of moles of solute particles (moles = mass / molar mass)
- R is the ideal gas constant (0.0821 L·atm/(K·mol))
- T is the temperature in Kelvin
- V is the volume of the solution in liters
- Convert the concentration of solute particles to moles by dividing it by the molar mass of the solute.
- The molar mass of urea is 60.06 g/mol.
- The molar mass of sucrose is 342.3 g/mol.
- The number of moles of urea is 4 g / 60.06 g/mol = 0.0666 mol.
- The number of moles of sucrose is 6.84 g / 342.3 g/mol = 0.02 mol.
- Convert the temperature to Kelvin by adding 273.15 to the Celsius temperature.
- 20 degrees Celsius = 20 + 273.15 =