If you can easily see the different parts that make up a mixture, you know that it is a mixture. * answer

A heterogeneous mixture (can see all of the parts)

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass