Why water comes out of salad when is sprinkled on it?

That's a great observation! It's not actually water coming *out* of the salad, but rather water that was already *in* the salad being released. Here's why:

* Osmosis: Plant cells, like those in lettuce, have cell walls that hold in water. The water inside the cells is more concentrated than the water you sprinkle on top. This creates a difference in concentration, driving water to move from the high-concentration area (inside the cells) to the lower-concentration area (the water you sprinkled). This process is called osmosis.

* Cell Structure: When you sprinkle water on the salad, it doesn't necessarily penetrate the cells very quickly. The water on the surface of the leaves pushes against the cells, causing them to release some of their internal water.

* Leaf Structure: Lettuce leaves are relatively thin and have a lot of surface area. This makes them prone to releasing water when they're wet.

Think of it like this: When you squeeze a sponge, water comes out. The water was already there, just trapped in the sponge. The same principle applies to salad leaves. The water you sprinkle on top isn't the same water that comes out, but it's the trigger that makes the leaves release their stored water.