Who was the first person to attempt to classify the living organisms on earth? what method did he use? , also give an example of the problem of using this type of system?

Aristotle was the first person to classify living organisms. He used the method of seeing whether they had red blood or not. Humans were classified under the classification of having red blood.

Hope this helps :)

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