Explain why, a small volume of water in a kettle can fill a kitchen with steam.

Bromine particles are almost twice as heavy as chlorine particles. Which gas will diffuse faster; bromine(vapour) or chorine? Explain your answer.

Why is a liquid (the hydraulic fluid) used to operate the brakes in a car?

Explain why, osmosis can be considered to be a special kind of diffusion. Classify the following into

(i) osmosis, and (ii) diffusion:

(a) swelling up of a raisin on keeping in water

(b) spreading of virus on sneezing

(c) earthworm dying on coming in contact with common salt

(d) shrinking of grapes kept in thick sugar syrup

(e) preserving of pickles in salt

(f) spreading of smell of cake being baked in the kitchen

(g) aquatic animals using oxygen dissolved in water during respiration

A student placed a gas jar containing air in the upside down position over a gas jar full of red-brown bromine vapours. He observed that the red brown colour spread upwards into the jar containing air. Based on this observation, the student concluded that it is only the bromine vapour which moves up and diffuses into air in the upper jar, the air from the upper jar does not move down by diffusion into the lower jar containing bromine vapours. Do you agree with this conclusion of the student? Give reason for your answer.