Across
1
Gas essential for breathing
3
Fourth state of matter
6
Reddish electrical conductor
7
Substance with pH below 7
8
Mass per unit volume
10
Hottest planet in solar system
11
Infectious microscopic agent
Down
2
Amplified beam of light
4
Tectonic landmass section
5
Element found in all living things
9
Group of similar cells
12
Naturally occurring inorganic solid