75% hydrogen
25% helium
2%carbon, nitrogen
At the center of every atom lies a small, dense "nucleus" that is positively charged.
Atom is the smallest unit of matter. It is made up of electrons, protons and neutrons. Electrons are negatively charged particles that are found scattered in different energy levels outside the nucleus. Protons are positively charged particles present inside the nucleus. Neutrons do not carry charge and found inside the nucleus. Thus, protons and neutrons make up the nucleus of an atom. Since, protons are positively charged and neutrons are uncharged particles, the charge of nucleus becomes positive.
D because Carbon and Oxygen form covalent compounds. I wasn't the greatest at chem., but I'm pretty sure this is correct :D let me know if I gave you the right answer.
