Which phenomenon occurs during the following changes?
$(a)$ Formation of clouds.
$(b)$ Drying of wet clothes.
$(c)$ Wax melts in the sun.
$(d)$ Size of naphthalene balls decreases.

Classify the following processes into osmosis or 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 pickles in salt.
$(f)$ Spreading of smell of cake being baked throughout the house.
$(g)$ Aquatic animals using oxygen dissolved in water during respiration.

$(a)$ Compare a block of wood,water,and air on the basis of the following:
$(i)$ Compressibility
$(ii)$ Particle motion
$(iii)$ Rigidity
$(b)$ Account for the following:
$(i)$ Gases exert pressure on the walls of the container.
$(ii)$ Liquids can be called fluids.

$(a)$ Arrange the following in the increasing order of $(i)$ Force of attraction $(ii)$ Intermolecular space: Iron nail,Kerosene,and Oxygen gas. $(b)$ Define the following terms: $(i)$ Rigidity $(ii)$ Compressibility $(iii)$ Diffusion.

Explain:
$(a)$ Sponge,though compressible,is a solid.
$(b)$ Gases completely fill the vessel in which they are kept.

Fill in the blanks :
$(a)$ Evaporation of a liquid at room temperature leads to a ........... effect.
$(b)$ At room temperature,the forces of attraction between the particles of solid substances are ........... than those which exist in the gaseous state.
$(c)$ The arrangement of particles is less ordered in the ........... state. However,there is no order in the ........... state.
$(d)$ ........... is the change of solid state directly to vapour state without going through the ........... state.
$(e)$ The phenomenon of change of a liquid into the gaseous state at any temperature below its boiling point is called ...........