The quenching of fluorescence depends on:

$0.27 \ g$ of a long chain fatty acid was dissolved in $100 \ cm^3$ of hexane. $10 \ mL$ of this solution was added dropwise to the surface of water in a round watch glass. Hexane evaporates and a monolayer is formed. The distance from edge to centre of the watch glass is $10 \ cm$. What is the height of the monolayer? [Density of fatty acid $= 0.9 \ g \ cm^{-3}, \pi = 3$]

$A$ cube of edge length $1 \ cm$ is divided into smaller cubes of uniform size of length $1 \ nm$. Assuming that no voids are present,the ratio of total surface area of all the cubes of $1 \ nm$ edge length to the surface area of the initial cube is

Which of the following is not a surface phenomenon?

Which of the following statements are not true?

The lubricating action of an oil is more if it possesses: