Across
1
Compound containing oxygen
4
The Red Planet
6
Preserved remains of ancient life
8
Glass that splits light into spectrum
9
Gas essential for breathing
12
Basic unit of life
13
Group of similar cells
Down
2
Unit of energy
3
Substance with pH above 7
5
Mass per unit volume
7
Curved glass that refracts light
10
Chemical element in table salt
11
Measure of matter in an object