(N/A) When kept in water,a raisin swells in size. This is due to a phenomenon known as 'Osmosis'.
Osmosis is the spontaneous net movement of solvent molecules from a region of higher solvent concentration (pure solvent) to a region of lower solvent concentration (solution) through a semi-permeable membrane.
In the case of a raisin,the water concentration outside is higher than inside the raisin. Thus,water enters the raisin through its semi-permeable skin,causing it to swell.
Three applications of osmosis are:
$i$. Movement of water from soil into plant roots and subsequently into the upper portion of the plant.
$ii$. Preservation of meat against bacterial action by adding salt.
$iii$. Preservation of fruits against bacterial action by adding sugar. Bacteria in canned fruit lose water through the process of osmosis,shrivel,and die.