Elaborate on the difference in natural occurrences between nuclear fission and nuclear fusion reactions. a) neither nuclear fission nor nuclear fusion reactions naturally occur on earth or outer space. b) nuclear fission reactions rarely occur naturally while nuclear fusion reactions occur in the stars. c) both nuclear fission and nuclear fusion reactions readily naturally occur in the pressure of the earth's core. d) nuclear fusion reactions do not naturally occur while nuclear fission reactions occur in the volcanoes.

Option B: Nuclear fission reactions rarely occur naturally while nuclear fusion reactions occur in the stars.

Nuclear fission reaction is defined as formation of two or more atoms by splitting of large atoms. On the other hand, nuclear fusion reaction is formation of large atom from small atoms.

The splitting of large atoms into small atoms (nuclear fission) generally does not occur naturally because it requires high speed neutrons and critical mass of the substance undergoing fission.

Nuclear fusion reaction occurs in stars such as sun because it requires extremely high energy to bring two more proton closer to each other by overcoming electronic repulsion.

Therefore, nuclear fission reactions rarely occur naturally while nuclear fusion reactions occur in the stars.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.