Question

Which of these is not a colligative property?

• A. Osmotic pressure
• B. Polymorphism
• C. Depression of freezing point
• D. Elevation in boiling point

Answer 1

The Correct Option is B

To determine which of the listed options is not a colligative property, let's first define what colligative properties are.

Colligative properties are properties of solutions that depend on the number of solute particles in a given amount of solvent and not on the nature of the solute particles. The key colligative properties are:

1. Osmotic Pressure: It is the pressure required to stop the flow of solvent molecules through a semipermeable membrane. It depends on the concentration of solute particles.
2. Depression of Freezing Point: Adding solute to a solvent lowers its freezing point. This effect is dependent on the number of solute particles.
3. Elevation in Boiling Point: The boiling point of a solvent increases when a solute is dissolved in it, again depending on the number of solute particles.

All the properties mentioned above are colligative because they depend only on the concentration of the solute particles, not the type of particle.

Now, let's look at the option Polymorphism. Polymorphism refers to a material being able to exist in more than one form or crystal structure. It is a property related to the nature of the solid and not related to the number of particles or their concentration in a solution. Therefore, this is not a colligative property.

Conclusion: The option that is not a colligative property is Polymorphism.