Across
1
Substance with pH below 7
4
Tectonic landmass section
5
Absolute temperature scale unit
7
Reddish electrical conductor
9
Blocking of light by a celestial body
12
Biological catalyst
Down
2
Center of an atom or cell
3
Mass per unit volume
6
Gas form of a liquid
8
Substance with pH above 7
10
Measure of matter in an object
11
Second lightest element