Across
1
Substance with pH above 7
3
Fourth state of matter
4
Icy body with a tail near the sun
7
Particle of light
9
Gas essential for breathing
11
Group of similar cells
Down
2
Blocking of light by a celestial body
5
Our home planet
6
Nerve cell in the brain
8
Solid with repeating atomic pattern
10
Unit of electric potential