Across
1
Gas essential for breathing
5
Unit of electric potential
6
Measure of matter in an object
7
Chemical element in table salt
11
Substance with pH below 7
Down
2
Unit of heredity
3
Preserved remains of ancient life
4
Nerve cell in the brain
8
Ball of burning gas in space
9
Naturally occurring inorganic solid
10
Compound containing oxygen
12
Second lightest element