question:
A pot of cold water was heated on a stove until the water boiled. Which of the following best explains why the water was able to boil?
OPTIONS:
- The hot stove absorbed cold from the pot.
- The cold water absorbed heat from the pot.
- The hot stove gave off heat to the surrounding air.
- The cold water gave off cold to the surrounding air.

answer:
The cold water absorbed heat from the pot.

question:
In addition to oxygen, which gases make up the largest percentage of Earth's atmosphere?
OPTIONS:
- hydrogen, helium, and water vapor
- hydrogen, methane, and ozone
- carbon dioxide, water vapor, and nitrogen
- carbon dioxide, methane, and helium

answer:
carbon dioxide, water vapor, and nitrogen

question:
Two pure substances combine to make a new substance. The new substance cannot be physically separated and has a different boiling point than each of the original substances. This new substance can best be classified as
OPTIONS:
- an atom.
- a mixture.
- an element.
- a compound.

answer:
a compound.

question:
Hydrochloric acid is added to a beaker containing a piece of zinc. As a result, zinc chloride is formed and hydrogen gas is released. This is an example of
OPTIONS:
- a chemical reaction
- a physical change
- photosynthesis
- evaporation

answer:
a chemical reaction