Question 85: Pumice stone is an example of –
(1) solid sol
(2) foam
(3) sol
(4) gel
Answer: Option (1)
Explanation:
A solid sol is a colloidal system in which solid particles are dispersed in a solid medium.
Pumice stone consists of gas bubbles trapped inside a solid matrix
formed during rapid cooling of volcanic lava.
These gas-filled cavities are uniformly distributed within the solid structure,
making pumice a colloidal system.
Since the dispersed phase behaves like a solid within a solid medium,
pumice stone is classified as a solid sol.
Therefore, the correct answer is option (1).