The correct answer is b. bimolecular
I believe that this atom is chlorine and the atom has an overall charge of zero.
Chlorine is chemical element which is atomic number 17 in the periodic table. Each chlorine atom has 17 protons (positively charged) in the nucleus balanced by 17 electrons (negatively charged) in the energy shells ( thus an overall charge of zero)
A matter in the solid phase has a fixed shape and volume.