7. Uranium-233 and Uranium-235 are the only two isotopes of uranium used as fuels in nuclear fission reactors. If you had 2.5 kg samples of each, which one would contain the least amount of the original
radioisotope after 1 billion years? Explain your answer. The half life of U-233 is 160,000 years, the
half-life of U-235 is about 700,000,000 years.

the law of conservation of mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. because atoms are only rearranged in a chemical reaction, there must be the same number of sodium atoms and chlorine atoms in both the reactants and products

the answer is option a.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.