Answer:
See below. Only Option 2 is correct:
2.Electrons are so small that it does not affect the mass of an atom.
Step-by-step explanation:
1.Electrons do not exist in all atoms. False. Atoms contain electrons.
2.Electrons are so small that it does not affect the mass of an atom.
True. Electrons are verrrrry small.
3.Electrons are do not contain mass.
False. The mass is too small to be of importance in standard chemical reactions. Nuclear scientists, however, pay attention. Particle accelerator experiments require knowledge of the electron's mass. And remember that since E=mc^2 [Energy = Mass x (Speed of Light)^2] even a small mass can have a lot of energy.
4.Electrons are not as important as protons and neutrons.
False. And don't let them hear you say they aren't important. They are the reason elements combine to make compounds. If you irritate them enough, they can release tons of energy in a reaction and put you on tomorrow's front page and news broadcast.