The statement "Addition of solutes to a solution causes an increase in its water potential" is not correct.

The correct statement is: Addition of solutes to a solution causes a decrease in its water potential.

Water potential is a measure of the potential energy of water molecules in a solution. When solutes are added to a solution, the water potential of the solution decreases. This is because the presence of solutes reduces the free energy of water molecules and lowers their potential to perform work or move freely.

The other statements are correct:

- The boiling point of an aqueous solution is higher than that of pure water. Adding solutes to water raises the boiling point because the presence of solutes disrupts the water molecule interactions and requires more energy to break the bonds and reach the boiling point.

- The vapor pressure of the water in a solution is lower than that of pure water. The presence of solutes reduces the ability of water molecules to escape into the gas phase, resulting in a lower vapor pressure compared to pure water.

- When a solution is separated from water by a semi-permeable membrane, water movement can be prevented by applying pressure to the solution. This process is known as reverse osmosis, where external pressure is applied to the solution to overcome the osmotic pressure and prevent water from moving through the membrane.

Therefore, the statement that is not correct is: Addition of solutes to a solution causes an increase in its water potential.