При сохранении произошла ошибка, попробуйте снова.
Если ошибка повториться, пожалуйста, напишите нам об этом в обратной связи - Написать сообщение!
4.5
Why an old egg floats and a fresh egg sinks.
A hen’s egg consists of the yolk and the white. These two things are heavier than water. So when you put an egg in water it sinks.
But in an egg which has become old, the yolk and the white produce gases which make the egg much lighter than it was before. Such an egg does not weigh as much as an equal quantity of water. If you put it in water, it will not sink. It floats because it is less heavy than the same quantity of water.
* * *
Do seeds breathe as people do?
Every living thing must breathe. Even eggs must breathe. Perhaps you have never thought that an egg is alive. But if you put an egg in a place where there is no air, it will die, and no chicken will come out of it.
The seed gets its oxygen from the air. You must not plant a seed too deeply, or it will not get enough oxygen and will die.
You may wonder that a seed must breathe, because you think that a living thing can breathe only with lungs, as people breathe. But you see that it is not so.
