A gel is a mixture of:

Correct option is D

(d) Liquid and solid

Explanation:

A gel is a colloidal system where a solid phase is dispersed in a liquid medium. The solid component forms a network structure, trapping the liquid within it, resulting in a semi-solid consistency. Examples include gelatin, hair gel, and jelly.

Key Points:

• Colloidal systems involve different phases mixed together.
• Gels are viscoelastic (behave like solids and liquids).
• Examples: Aloe vera gel, toothpaste, and agar.
• Jelly is an example of a hydrogel.
• Used in cosmetics, pharmaceuticals, and food products.

Analysis of Other Options:

• (a) Liquid and liquid – Incorrect; such mixtures form emulsions (e.g., milk, mayonnaise).
• (b) Solid and solid – Incorrect; forms alloys, not gels.
• (c) Gas and gas – Incorrect; gases mix completely, forming homogeneous mixtures.

Additional Information:

• Gels can be reversible or irreversible (thermoreversible gels like gelatin can liquefy when heated).
• Hydrogels absorb water, making them useful in medical applications