资料题：One gain of salt contains（　）。

Atoms are all around us.They are the bricks of which everything is made.Many millions of atoms are contained in just one grain of salt, but despite their small size they are very important.The way an everyday object behaves depends on what kinds of atoms are in it and how theyact.For instance, you know that most solid objects melt if they get hot enough.Why is this? It is the eat of the heat an the object's atoms.All atoms move constantly.When they are hot,they move faster.Usually the atoms in an object hold together and give the object is shape.But if the object grows hot, its atoms move so fast that they break the force that usually holds them together.They move out of their usual places 60 that the object loses its shape.Then we say that the abject is melting.