Explanation:

Drying is a process of removing moisture from a material. Drying under vacuum is a technique used to reduce the drying temperature. In this process, a vacuum is created in the dryer chamber, which reduces the pressure inside the chamber. This reduction in pressure lowers the boiling point of water, which makes the drying process faster and more efficient.

The answer to the given question is option 'B' because drying under vacuum is carried out to reduce the drying temperature. Let us understand this in detail.

Drying temperature and its effect on materials:

Drying temperature is an essential parameter in the drying process. The drying temperature depends on the type of material being dried and the moisture content in it. The drying temperature should be chosen carefully because high temperatures can damage the material being dried, while low temperatures can lead to a slow drying process.

Drying under vacuum:

Drying under vacuum is a technique used to reduce the drying temperature. In this process, the pressure inside the dryer chamber is reduced, which lowers the boiling point of water. This reduction in pressure makes the drying process faster and more efficient. The vacuum also helps to remove the moisture from the material, making it easier to dry.

Advantages of drying under vacuum:

Drying under vacuum has several advantages over conventional drying techniques. Some of them are:

1. Faster drying: Drying under vacuum is faster than conventional drying techniques because the pressure inside the chamber is reduced, which lowers the boiling point of water.

2. Lower temperature: Drying under vacuum requires a lower temperature, which reduces the risk of damage to the material being dried.

3. Improved quality: Drying under vacuum can improve the quality of the material being dried because it reduces the risk of overheating and damage.

Conclusion:

Drying under vacuum is a technique used to reduce the drying temperature and make the drying process faster and more efficient. It is carried out to dry materials that have high bound moisture content. This technique has several advantages over conventional drying techniques, including faster drying, lower temperature, and improved quality of the material being dried.