Which of the pair(s) are correctly matched?

Choose the correct answer from the options given below:

B and E only

The correct answer is option 2. B and E only.

Let us go through each pair in more detail to clarify why certain examples fit their colloid type and others do not.

A. Liquid in solids: Gemstones

In a liquid-in-solid colloidal system, a liquid phase is dispersed throughout a solid medium. This type of system is called a gel. Common examples of such colloids are jellies or butter, where liquid (such as water) is dispersed in a solid matrix. Gemstones are typically formed by crystallization processes that produce a solid crystalline structure. They are not colloidal in nature, nor do they contain any liquid phase within a solid matrix. They are pure solids rather than a dispersed phase. The example of gemstones is incorrect for a liquid-in-solid colloid, because gemstones are solid materials, not colloids with a dispersed liquid phase.

B. Solid in liquid: Cell fluids

In a solid-in-liquid colloidal system, small solid particles are dispersed in a liquid medium. This is known as a sol. A common example is paint or muddy water, where solid particles are suspended in liquid. Cell fluids (or cytoplasm) are composed of a water-based solution in which solid particles like proteins, enzymes, ions, and organelles are suspended. These solid particles are dispersed within the liquid cytosol, behaving as a colloidal system. This example is correct. Cell fluids are indeed solid-in-liquid colloidal systems, where solid biomolecules are dispersed in a liquid medium.

C. Solid in gas: Mist

In a solid-in-gas colloid, solid particles are dispersed in a gaseous medium. This type of colloid is called an aerosol. Common examples include smoke (solid particles in air) or dust particles in air. Mist is composed of tiny liquid droplets dispersed in air (a gas). This makes it a liquid-in-gas colloidal system (also an aerosol), not a solid-in-gas system. Mist forms when water vapor condenses into liquid droplets suspended in the air. This example is incorrect. Mist is a liquid-in-gas colloid, not a solid-in-gas colloid.

D. Gas in liquid: Pumice stone

A gas-in-liquid colloid is called a foam, where gas bubbles are dispersed in a liquid medium. Examples include whipped cream or soap lather, where air bubbles are dispersed in water or another liquid. Pumice stone is a porous volcanic rock that contains trapped gas bubbles within a solid matrix. This makes it a gas-in-solid colloid, where the gas is trapped in a solid structure, not in a liquid. This example is incorrect. Pumice stone is a gas-in-solid colloid, not gas-in-liquid.

E. Liquid in solid: Butter

A liquid-in-solid colloidal system, or gel, occurs when liquid droplets are dispersed in a solid matrix. An example is jelly or cheese, where water or another liquid phase is trapped within a solid structure. Butter is a gel, where water droplets are dispersed within a solid fat matrix. The fat solidifies, trapping the liquid within it, forming a colloidal system. This example is correct. Butter is a classic example of a liquid-in-solid colloid.

Thus, the correct answer is Option 2: B and E only.