A cucumber slice placed in pure water increases size?

Yes, a cucumber slice placed in pure water will increase in size. This is due to a process called osmosis. Osmosis is the movement of water molecules from an area of high water concentration to an area of low water concentration, through a semipermeable membrane. The cucumber slice is a semipermeable membrane, which means that it allows water molecules to pass through it, but it does not allow the larger solute molecules inside the cucumber to pass through. As a result, water molecules move from the pure water on the outside of the cucumber slice into the cucumber slice, causing it to swell and increase in size.