Question

all of the following statements are true of nuclear fusion except...
select one:
a. extremely high temperatures are needed to start the reaction.
b. hydrogen, the reactant, is scarce.
c. two light nuclei react to form a heavier nucleus.
d. the products of the process may be radioactive.

which of the following elements is often used as a reactant in a nuclear fission reactor?

select one:
a. hydrogen
b. uranium
c. carbon
d. boron

Explanation:

For the first question:

• Nuclear fusion requires extreme temperatures to overcome electrostatic repulsion between nuclei, so option a is true.
• Hydrogen (and its isotopes like deuterium) are abundant in water and cosmic sources, so option b is false.
• Fusion is defined as light nuclei combining into a heavier nucleus, so option c is true.
• Some fusion products can be radioactive, so option d is true.

For the second question:

• Nuclear fission reactors use heavy, fissile nuclei. Uranium-235 is the most common reactant, as it readily undergoes fission when bombarded with neutrons. Hydrogen is used in fusion, carbon and boron are not primary fission reactants.

Answer:

1. b. Hydrogen, the reactant, is scarce.
2. b. Uranium