What did Aristotle believe? A. That matter did not exist in the physical world
B. That the scientific method should be used to test ideas
C. That all matter was composed of earth, fire, water, and air
D. That all matter was composed of tiny atoms

C.) That all matter was composed of earth, fire, water and air

Explanation:

Just took the test

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.