The correct answer is B. Liquid in a liquid.
An emulsion is a mixture of two or more immiscible liquids, one of which is dispersed in the other in the form of small droplets. The droplets are typically much smaller than the wavelength of light, which is why emulsions are often transparent.
There are two main types of emulsions: oil-in-water emulsions and water-in-oil emulsions. In oil-in-water emulsions, the oil droplets are dispersed in the water phase. In water-in-oil emulsions, the water droplets are dispersed in the oil phase.
Emulsions are often used in cosmetics, food, and pharmaceuticals. They can also be used to stabilize suspensions of particles in liquids.
Here is a brief explanation of each option:
- A. Gas in a liquid: This is not an emulsion. A gas in a liquid is called a foam.
- B. Liquid in a liquid: This is an emulsion. An example of an emulsion is milk, which is a mixture of water and fat.
- C. Liquid in a gas: This is not an emulsion. A liquid in a gas is called an aerosol.
- D. Gas in a solid: This is not an emulsion. A gas in a solid is called a solid foam.