What evidence indicates that the nuclei of strontium-90 atoms are unstable?
a) strontium-90 electrons are in the excited state.
b) strontium-90 electrons are in the ground state.
c) strontium-90 atoms spontaneously absorb beta particles.
d) strontium-90 atoms spontaneously emit beta particles.

How does a catalyst increase the speed of a reaction? a. the catalyst eliminates the activated complex stage, allowing products to form immediately. b. the catalyst lowers the energy level of the reactants, making it easier for them to react. c. the catalyst makes it easier for the activated complex to form, lowering the activation energy. d. the catalyst raises the energy level of the products, making the reaction finish sooner. reset next