Across
1
Icy body with a tail near the sun
4
Biological catalyst
5
Center of an atom or cell
8
Unit of electric potential
Down
2
Curved glass that refracts light
3
Nerve cell in the brain
6
Particle of light
7
Gas essential for breathing
Icy body with a tail near the sun
Biological catalyst
Center of an atom or cell
Unit of electric potential
Curved glass that refracts light
Nerve cell in the brain
Particle of light
Gas essential for breathing