Which of the following is correct concerning hess's law?
a. the change of enthalpy of a reaction can be found be subtracting the enthalpy of the products from the enthalpy of the reactants.
b. the change in enthalpy can be found be subtracting the enthalpy of the reactants from the enthalpy of the products.
c. the change in enthalpy can be found by adding the enthalpies of the individual thermochemical reactions of a chemical reaction.
d. the change in enthalpy can be found by subtracting the enthalpies of the individual thermochemical reactions of a chemical reaction.

The statement that is correct concerning Hess's law is D. Hess' Law of Constant Heat Summation expresses that paying little respect to the numerous stages or ventures of a response, the aggregate enthalpy change for the response is the whole of all progressions. This law is an indication that enthalpy is a state work.

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.