After world war i, senators who opposed united
states participation in the league of nations
argued that american membership in the
organization would
(1) limit the power of the president
(2) make trade with nonmember nations more
difficult
(3) force the country to end traditional military
alliances
(4) involve the nation in future world conflicts

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.  

level 4 to level 2 : ))