Across
1
Substance with pH above 7
3
Natural satellite of Earth
4
Fourth state of matter
7
Icy body with a tail near the sun
10
Amplified beam of light
Down
2
Center of an atom or cell
5
Curved glass that refracts light
6
Unit of electric potential
8
Tectonic landmass section
9
Measure of matter in an object
11
Smallest unit of an element
12
Blocking of light by a celestial body