The oxidation of both cu and zn (both present in a penny) with nitric acid generates complex ions of cu and zn in solution. it also produces nitrogen dioxide, a brown, toxic gas. for this reason, where must the dissolving of the penny be carried out?

intermolecular forces are the forces between molecules or particles.

there are two kinds of van der waals forces: weak london dispersion forces and stronger dipole-dipole forces.

in molecule of water there are dipole-dipole forces between negatively charged oxygen from one molecule of water and positively charger hydrogen of another molecule of water.

hydrogen bond is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (h), covalently bound to a highly electronegative atom such as flourine (f), oxygen (o) and nitrogen (n) atoms.