Which statement best describes a mole? It is 12 units of a given substance.
It contains 6.02 Times. 1023 grams of sodium chloride.
It is the mass of 12 carbon atoms.
It contains 6.02 Times. 1023 particles of a given substance.

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.  

false it is never safe to stand on the top step of a ladder provided it is braced properly.