Hint: The properties of solution that depend only on the total number of soluble particles (molecules or ions), and not on nature of solute particles in solution are called Colligative properties.
Complete step by step solution:
Surface tension is the attractive force found in liquids which is responsible for pulling surface molecules in the rest of the liquid.
Surface tension is property of substance which depend on nature of solute particle so surface tension a not colligative property
Viscosity of a fluid is a measure of its resistance to deformation at a given rate. It is defined by the concept of the thickness of fluid layers for liquid.
Viscosity property of substances which depend on the nature of solute particles so viscosity a not colligative property.
Refractive index refers to the measure of the bending of a ray of light when it passes from one medium to another medium.
Refractive index of substances which depend on the nature of solute particles so it is not a colligative property.
Osmotic pressure is directly proportional to molarity and molarity is dependent on the number of solute particles and is independent on the nature of the solute particle.
Hence osmotic pressure is a colligative property.
Note: Make sure to remember that the Colligative Properties of solutions depend only on the total number of soluble particles (molecules or ions), and not on the nature of solute particles.
