Choose the correct alternative.

1. What is the heat source of the Sun?

rapid combustion
electricity
nuclear reactions
friction
slow combustion

2. Why does the Sun radiate heat?

Hydrogen burns in the Sun.
Helium burns in the Sun.
Carbon burns in the Sun.
Nuclear reactions take place in the Sun.
Chemical reactions take place in the Sun.

3. Which type of nuclear reaction takes place inside stars?

fission
fossil
photon
fusion
solar

4. Which type of nuclear reaction takes place in nuclear power plants?

fission
fossil
photon
fusion
solar

5. Which metal is used as the raw material in nuclear power plants?

copper
lead
uranium
platinium
zinc