When a limp carrot is placed in water, it can become firm again due to the process of osmosis. Here’s a simple explanation of how this happens:

1. Limp Carrot: When a carrot becomes limp, it typically means that it has lost water and is dehydrated. The loss of water causes the cells within the carrot to shrink and the overall structure to become soft and flaccid.
2. Osmosis in Action: When the limp carrot is placed in water, osmosis comes into play. Water molecules naturally move from an area of higher water concentration (in this case, the water) to an area of lower water concentration (inside the carrot cells) through the semi-permeable membrane of the carrot’s cells.
3. Rehydration Process: As the carrot is immersed in water, the water molecules move into the cells of the carrot through osmosis. This influx of water helps to rehydrate the cells, causing them to swell and regain their turgidity.
4. Regained Firmness: As the carrot cells absorb water through osmosis, they expand and become turgid once again. This rehydration process leads to the restoration of the carrot’s firmness, making it crisp and rigid.

In summary, placing a limp carrot in water allows for the movement of water molecules into the carrot cells through osmosis. This rehydrates the cells, restores their turgidity, and ultimately makes the carrot firm again.