When glycerine is added to a litre of water which of the following behaviour is observed.

Options

A. Water evaporates more easily
B. The temperature of water is increased
C. The freezing point of water is lowered
D. The viscosity of water is lowered

Answer

To solve the question regarding the behavior observed when glycerine is added to a liter of water, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components**:
- Glycerine is a type of alcohol that is soluble in water.
- When glycerine is added to water, it acts as a solute, while water is the solvent.

**Hint**: Identify the roles of the substances involved (solute vs. solvent).

2. **Effect on Solvent Molecules**:
- When glycerine is added to water, it dilutes the water molecules. This means that the concentration of water molecules decreases as glycerine molecules occupy some of the space in the solution.

**Hint**: Consider how adding a solute affects the concentration of the solvent.

3. **Raoult's Law**:
- According to Raoult's Law, the addition of a solute (glycerine) to a solvent (water) results in a decrease in the vapor pressure of the solvent. This is because the presence of solute molecules reduces the number of solvent molecules at the surface that can escape into the vapor phase.

**Hint**: Recall the relationship between solute concentration and vapor pressure.

4. **Freezing Point Depression**:
- The decrease in vapor pressure leads to a phenomenon known as freezing point depression. This means that the freezing point of the solution (water + glycerine) will be lower than that of pure water.

**Hint**: Remember that colligative properties, like freezing point depression, depend on the number of solute particles in solution.

5. **Evaluating the Options**:
- A) Water evaporates more easily: This is incorrect; the evaporation rate decreases due to lower vapor pressure.
- B) The temperature of water increases: This is incorrect; the temperature decreases due to the freezing point depression.
- C) The freezing point of water is lowered: This is correct; as explained, the freezing point is indeed lowered.
- D) The viscosity of water is lowered: This is incorrect; the viscosity may not significantly change with the addition of glycerine.

**Hint**: Analyze each option based on the principles discussed.

### Conclusion:
The correct behavior observed when glycerine is added to a liter of water is that **the freezing point of water is lowered** (Option C).