Which process repeatedly moves matter between different forms on earth?
a. cycle
b. natural law
c. closed system
d. conservation of matter

Which of the following harmful chemicals are found in tobacco smoke? a. carbon monoxide b. carbon dioxide c. nicotine b. carbon dioxide d. both a and c

If two students are running down the hall toward each other, trying to get to class, and they have the same mass and acceleration, what will happen when they collide? will their forces cancel out or will each one experience a reaction?

What are the necessary conditions for fusion?