Across
1
Compound containing oxygen
4
Positive particle in nucleus
7
Substance with pH below 7
8
Preserved remains of ancient life
9
Center of an atom or cell
Down
2
Naturally occurring inorganic solid
3
Unit of electric potential
5
Mass per unit volume
6
Amplified beam of light
7
Smallest unit of an element
10
Magnetic metallic element
11
Nerve cell in the brain