When animals use energy, they produce OPTIONS:
- nitrogen
- iron sulfide
- oxygen
- carbon dioxide
A: carbon dioxide

Which of the following processes is an important part of star formation? OPTIONS:
- nuclear fusion
- nuclear fission
- molecular fusion
- molecular fission
A: nuclear fusion

Which item would a magnet attract? OPTIONS:
- iron nail
- wool cloth
- wooden stick
- glass marble
A: iron nail

Which of the following is most likely to cause water to change from one state of matter to another state of matter? OPTIONS:
- increased precipitation
- the weathering of rocks
- a decrease in wind speed
- a change in air temperature
A:
a change in air temperature