Which of the following is two or more atoms (same or different) bound together?
a. element
b. molecule
c. pure substance
d. mixture

The correct answer is option B. A molecule is two or more atoms (same or different) bound together. It is the smallest particle in a chemical element or compound. Molecules are held together by chemical bonds. These bonds are formed by the sharing or transfer of electrons between atoms.

The atomic number is the same as the amount of electrons and protons. For example:
Oxygens atomic number is 8 so the proton and electron count is 8.
Hydrogens atomic number is 1 so the proton and electron count is 1.