1. which of the following objects would require the use of a large-scale model?

a. an atom
b. a car engine
c. a frog's heart
d. the mississippi river
2. scott stated the following series of observations. which represents a theory?

a. i observed three stars in the sky.
b. the stars give off light.
c. light travels at 300,000 kilometers per second.
d. stars are balls of hot gases.