According to the theory of plate tectonics, which forces cause the movement of plates in the earth's crust?

a. magnetism and solar radiation
b. earthquakes and volcanic eruptions
c. convection and the moons gravitational pull
d. convection and gravity

In a particular chemical reaction, the energy of the reactants is 30 kj and the energy of the products is 5 kj. 
 the maximum energy of the system is 40 kj. sketch a potential energy diagram for this reaction. make sure to label the energy of the reactants, the energy of the products, the activation energy, and the enthalpy change for the reaction.