Non-Volatile Nature of Sugar in a Sugar Solution

When considering a sugar solution, which is a mixture of sugar and water, it is important to understand the behavior of its components upon vaporization. In this case, the question asks why only water evaporates while sugar remains in the solution. The correct answer is option 'B' - Non-Volatile.

Explanation:

1. Volatility of Substances:
- Volatility refers to the tendency of a substance to vaporize or evaporate.
- Volatile substances have a high vapor pressure and readily transform from the liquid phase to the gas phase at a relatively low temperature.
- Non-volatile substances, on the other hand, have a low vapor pressure and do not easily vaporize at normal temperatures.

2. Sugar and Water:
- Sugar, chemically known as sucrose (C12H22O11), is a non-volatile compound.
- It has a relatively high molecular weight and a complex structure, which makes it less likely to evaporate compared to simpler molecules.
- Water (H2O), on the other hand, is a volatile compound due to its relatively low molecular weight and simple structure.

3. Behavior of Sugar Solution:
- When a sugar solution is heated or undergoes vaporization, the water component of the solution will evaporate.
- The heat energy supplied to the solution causes the water molecules to gain enough kinetic energy to overcome the intermolecular forces holding them together in the liquid phase.
- As a result, water molecules escape from the liquid phase and enter the gas phase, forming water vapor.
- However, the sugar molecules, being non-volatile, remain in the liquid phase as the water evaporates.
- This is because the intermolecular forces between sugar molecules are relatively strong, and their molecular structure does not favor easy vaporization.

Conclusion:
In summary, in a sugar solution, only water evaporates while sugar remains in the liquid phase because sugar is a non-volatile compound. Its complex molecular structure and strong intermolecular forces prevent it from easily vaporizing at normal temperatures. On the other hand, water, being a volatile compound, readily evaporates due to its simpler structure and lower molecular weight.