While burning coal and charcoal, you notice that coal releases more heat than charcoal. That means that the is in charcoal than in coal.
Word Bank:
gravitational energy lower chemical potential energy higher elastic energy lower chemical potential energy
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It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).

I'm sorry but i'm only grade

Ithink about 50 % of an original isotope's number of atoms remain