Across
1
Gas form of a liquid
3
Path of a planet around the sun
4
Nerve cell in the brain
7
Unit of electric potential
8
Mass per unit volume
9
Second lightest element
11
The Red Planet
12
Magnetic metallic element
Down
2
Icy body with a tail near the sun
3
Gas essential for breathing
5
Fourth state of matter
6
Glass that splits light into spectrum
10
Reddish electrical conductor
13
Hottest planet in solar system