What is meant by nuclear energy?

• nuclear reaction in which small and light nuclei fuse to form a heavier nucleus while releasing a large amount of energy

• atomic energy, released during nuclear reactions such as radioactive decay, nuclear fission and nuclear fusion

• nuclear reaction when a heavy nucleus splits into two or more lighter nuclei while releasing a large amount of energy

• the time taken for a sample of radioactive nuclei to decay to half of its initial number

What causes a substance to be radioactive?

• an unstable nucleus

• elements with an atomic number above 125

• substance decays over time

• contaminated sewage

When a heavy nucleus splits into two or more lighter nuclei, releasing a tremendous amount of energy. What is the name of this reaction?

• Nuclear fusion

• Nuclear fission

What are the optimal conditions for nuclear fusion to occur?

• High volume

• Low velocity

• Extremely high temperature and pressure

• High mass defect

A chain reaction takes place because

• the energy released during the nuclear reaction is very high

• the process is uncontrolled

• heavy nucleus is highly radioactive

• the number of neutrons released is continuously multiplying as time increases

How does the Sun provide the Earth with light and heat energy?

• Radioactive radiations

• Half-life

• Nuclear fusion

• Nuclear fission

What distinguishes nuclear fusion from nuclear fission?

• Nuclear fusion does not produce energy, whereas nuclear fission does

• The result of nuclear fusion is a larger atomic nucleus

• Nuclear fission does not produce energy, whereas nuclear fusion does

• The result of nuclear fission is a bigger atomic nucleus

Where does nuclear fission take place?

• Nuclear reactor

• Battery

• Dam

• Lightning

Nuclear reactions involve changes to the nucleus of an atom. This includes

• protons

• electrons

• neutrons

Why is nuclear fusion regarded as a safer alternative to nuclear fission?

• They are equally unsafe

• Fusion is a chain reaction that must be kept under control or it will become uncontrollable

• Fission requires energy to continue, so we can halt it by removing energy

• Fusion has no chain reaction involved