Which one of the following statement is correct in respect of fluids?

(a) What is Brownian motion? Draw a diagram to show the movement of a particle (like a pollen grain) during Brownian motion.

(b) In a beam of sunlight entering a room, we can sometimes see dust particles moving in a haphazard way in the air. Why do these dust particles move?

When a crystal of potassium permanganate is placed at the bottom of water in a beaker, the water in the whole beaker turns purple on its own, even without stirring. This is an example of:

A few substances are arranged in the increasing order of ‘forces of attraction’ between their particles. Which one of the following represents the correct arrangement?

In which of the following conditions, the distance between the molecules of hydrogen gas would increase?

(i) increasing pressure on hydrogen contained in a closed container

(ii) some hydrogen gas leaking out of the container

(iii) increasing the volume of the container of hydrogen gas

(iv) adding more hydrogen gas to the container without increasing the volume of the container