Which statement best describes a foam?

Which statement best describes a foam?

• A. A colloid where gas particles are dispersed throughout a liquid.
• B. A homogeneous mixture of liquids.
• C. A solution of gas in a liquid.
• D. A suspension of solids in a gas.

Answer: (A)

Foams are a type of colloid where a gas is dispersed throughout a liquid. In a foam, countless tiny gas bubbles are spread in the liquid phase, giving a bubbly, airy texture as seen in whipped cream or shaving foam. This is different from a true solution, where a gas would be dissolved on a molecular level in the liquid rather than forming visible bubbles. It’s also different from a suspension of solids in a gas (like dust in air), where solid particles, not gas bubbles, are dispersed in a gas. So the statement describes the gas-in-liquid colloidal structure that defines a foam.

Foams are a type of colloid where a gas is dispersed throughout a liquid. In a foam, countless tiny gas bubbles are spread in the liquid phase, giving a bubbly, airy texture as seen in whipped cream or shaving foam. This is different from a true solution, where a gas would be dissolved on a molecular level in the liquid rather than forming visible bubbles. It’s also different from a suspension of solids in a gas (like dust in air), where solid particles, not gas bubbles, are dispersed in a gas. So the statement describes the gas-in-liquid colloidal structure that defines a foam.