*Question*
Answer the following question given this paragraph: For a star to form, gravity pulls gas and dust into the center of the nebula. As the material becomes denser, the pressure and the temperature increase. When the temperature of the center becomes hot enough, nuclear fusion begins. The ball of gas has become a star!. Q: For a star to form, what force pulls gas and dust into the center of the nebula? Choices: - weight - centrifugal force - motion - gravity A:
**Answer**
gravity

*Question*
Answer the following question given this paragraph: Chordates include vertebrates and invertebrates that have a notochord. Chordates also have a post-anal tail, dorsal hollow nerve cord, and pharyngeal slits. Vertebrate chordates have a backbone, while invertebrate chordates do not. Invertebrate chordates include tunicates and lancelets; both are primitive marine organisms. Q: What do vertebrate chordates possess that invertebrate chordates do not? Choices: - parasite - Thumb - Milk production - backbone A:
**Answer**
backbone

*Question*
Answer the following question given this paragraph: Bile salts are secreted into the small intestine to aid in the digestion of fats. Q: What type of salts are secreted into the small intestine to aid in the digestion of fats? Choices: - zinc - Table Salt - sodium - bile A:
**Answer**
bile

*Question*
Answer the following question given this paragraph: Ionic bonds are electrostatic attractions between two oppositely charged ions. Ions can be formed and then bonded when metal atoms donate their valence electrons to nonmetal atoms. Q: Ionic bonds are electrostatic attractions between two oppositely charged what? Choices: - molecules - gasses - compounds - ions A:
**Answer**
ions