Across
1
Gas essential for breathing
4
Hottest planet in solar system
5
Curved glass that refracts light
7
The Red Planet
9
Fourth state of matter
12
Positive particle in nucleus
Down
2
Preserved remains of ancient life
3
Basic unit of life
6
Ball of burning gas in space
8
Measure of matter in an object
10
Particle of light
11
Mass per unit volume
13
Element found in all living things