This is because the water vapour in the air condenses on the cold surface of the apple.
Since the apple is cold, the water vapour in the air condenses on the surface of the apple. This is why it becomes wet with water.
Water is evaporated faster outside a refrigerator.
Nothing ,if the refrigerator is working properly. If you put water in the freezer it will become ice.
It's condensation
If an object is cold enough, it will cause the water in the air around it to condense from gaseous form to liquid form, on the surface of the object. This is because there is only a certain amount of water that air can hold at a specific temperature. Hot air can hold more water than cold air, so if hot (or warm) air is cooled, then it will not be able to hold all the water it contains. This is what happens with the apple. The apple cools the air near it, and some of the water comes out of the air.
more of a straight science question than a culinary science one.
but you just put the water in the refrigerator
The stain under the water spout on the outside of your refrigerator door is probably "boiler scale." That is the minerals that are left when water evaporates. Commercial products exist to get rid of bathtub scum. They might work. Vinegar also might work. You do not want to use anything that will scratch the finish.
Because when they are kept in the fridge, fruits such as apples will lose water, and their sugar will crystalise, causing themselves to become sweeter.
I think they get rotten because they are left untendered to. Probably are left outside the refrigerator or no water or sun whe they are still on the dirt.
It melts into liquid (water)
Wash the outside of the apple with hot water to remove the wax that growers put on them before they are sent to market. Let it dry and try again. Hooweestik.