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.

(N/A) Osmosis: Water enters the raisin due to a higher water concentration outside.
$(b)$ Diffusion: Virus particles move from a region of higher concentration to lower concentration in the air.
$(c)$ Osmosis: Water moves out of the earthworm's body due to the high salt concentration outside (exosmosis).
$(d)$ Osmosis: Water moves out of the grapes into the hypertonic sugar syrup.
$(e)$ Osmosis: Salt creates a hypertonic environment,causing water to move out of the cells of the pickles (exosmosis).
$(f)$ Diffusion: Aroma molecules move from the cake to the surrounding air.
$(g)$ Diffusion: Dissolved oxygen moves from water into the aquatic animal's body across the respiratory surface.