Answer: They are called substances and mixtures
Explanation:
The *independent* variable is the one that you always can control. However, the dependent variables are not since they **depend** on another.
Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances.
Bohrs model says that electrons move in fixed shells (which have fixed distances) around the nucleus of an atom.
then the electrons and protons would have a even amount of negetive electric charges
