Detailed Explanation:

Correct Answer: ✅ 1 Only (Option A)

Hydrogels are three-dimensional polymer networks that can absorb and retain large amounts of water. Their biocompatibility and controlled swelling properties make them highly useful in medical applications.

✅ Statement I is Correct: Hydrogels are widely used in controlled drug delivery because they can absorb water and release medicines gradually at a desired rate.

❌ Statement II is Incorrect: Mobile air-conditioning systems use refrigerants, compressors, and heat exchangers. Hydrogels are not standard components in these cooling systems.

❌ Statement III is Incorrect: Industrial lubricants are generally oil-based or synthetic formulations. Hydrogels do not possess the required lubrication properties for industrial use.

Short Notes: Hydrogels

• Hydrogels are water-absorbing polymer networks capable of holding large amounts of water.

• They can contain up to 90–99% water while maintaining their structure.

• Widely used in controlled drug delivery systems.

• Used in contact lenses, wound dressings, and tissue engineering.

• Most hydrogels are biocompatible and non-toxic.

• They respond to changes in pH, temperature, and moisture.

• Hydrogels are important materials in biomedical engineering and regenerative medicine.