Hydrogen is located on the left side of the periodic table in the same column as the alkali metals, but it has characteristics of a nonmetal. Which of the following is a physical property of hydrogen? OPTIONS:
- Hydrogen can bond to itself.
- Hydrogen makes positive ions.
- Hydrogen is a gas at room temperature.
- Hydrogen is combustible.
A: Hydrogen is a gas at room temperature.

All the ponds in an area dried up during a drought. The population of which of the following animals that live in the area is most affected by the drought? OPTIONS:
- deer
- frog
- hawk
- squirrel
A: frog

The difference between the atomic number of an element and the element's atomic mass is the number of OPTIONS:
- ions.
- protons.
- electrons.
- neutrons.
A: neutrons.

Which system supports the body, protects internal organs, and makes blood cells? OPTIONS:
- muscular system
- circulatory system
- nervous system
- skeletal system
A:
skeletal system