Across
1
Particle of light
4
Path of a planet around the sun
5
Unit of electric potential
6
Nerve cell in the brain
7
Absolute temperature scale unit
9
Unit of heredity
11
The Red Planet
Down
2
Second lightest element
3
Mass per unit volume
4
Gas essential for breathing
8
Icy body with a tail near the sun
10
Push or pull on an object