A foundry worker places a 5.78 kg sheet of cobalt at a temperature of 11°C on top of a 16.6 kg sheet of lead at 63°C. Assuming no heat is lost to the surroundings, calculate the final temperature of the two sheets of metal.

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.  

they are called fossil fuels