Question

The appropriate relation between the surface area of any solid with that of the particle size can be stated as

(a) Surface area of any solid increases with increase in particle size

(b) Surface area of any solid is always equal to the particle size

(c) Surface area of any solid increases with decrease in particle size

(d) Surface area of any solid doesn’t depend at all on the particle size

The question was posed to me in an online interview.

The question is from Solid State Reaction in section Preparative Methods of Solid State Chemistry

Answer 1

The correct choice is (c) Surface area of any solid increases with decrease in particle size

To explain: Explanation:  Surface area is always inversely related with the particle size. In the form of a single crystal, a few grams of solid has a surface area about to equal to the area of a large postage stamp. In the form of a finely divided powder, its surface area is about equal to the area of a hundred meter running track. Hence surface area increases with decrease in particle size.