Q: The smallest units of matter that retain the unique properties of an element are known as what? A:

OPTIONS:
- protons
- molecules
- neutrons
- atoms

Answer: atoms

Q: What did volcanic gases help to form on earth? A:

OPTIONS:
- water
- plants
- rocks
- atmosphere

Answer: atmosphere

Q: What element is essential for amino acid and nucleic acid production? A:

OPTIONS:
- oxygen
- carbon
- hydrogen
- nitrogen

Answer: nitrogen

Q: What type of experiment involves two identical experiments carried out side-by-side, with and without an independent variable? A:

OPTIONS:
- trial run
- defined experiment
- blind test
- controlled experiment

Answer:
controlled experiment