When the power goes off, Jack does not have a flashlight so he uses a glow stick to provide light. He is not very satisfied with how long the glow stick lasts. What could Jack do to improve how long his glow stick lasts?

yes it is balanced

it means there are 3 atoms of oxygen

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.