How do the isotopes of helium compare to one another?

In which layer of earth do most earthauakes occur a_ inner core b_outer core c_mantle d_crust

Which statement is usually true about the relationship between activation energy and reaction rates? low activation energy barriers result in low rates. high activation energy barriers result in low rates. low activation energy barriers result in no reaction. high activation energy barriers result in no reaction.

Which statement best describes the flow of energy in this scenario