What would happen to the boiling point of water at 8000 above sea level, where the air pressure is lower?

The boiling point will be lower, because water boils when its vapour pressure is equal to atmospheric pressure. If you are at 8 000 m above sea level, the air pressure is lower than one atmosphere and the equilibrium between the water and air pressures will be reached before.

Vander waals forces are inter molecular bonds that exist within molecules of the same substance. a water molecule is made up of oxygen and hydrogen atoms which share electrons between each other. the vander waals forces are forces that exist between multitude of different  molecules of water. dipole dipole forces is the type of vander waals force that exist in water. the oxygen atom which is more electronegative pulls the shared electron closer to itself thus generating a partial negative charge while the hydrogen acquire a partial positive charge. these two different charges causes attraction to occur in water molecules.