Across
1
Unit of force
5
Gas essential for breathing
7
Unit of energy
8
Biological catalyst
9
Push or pull on an object
12
Icy body with a tail near the sun
Down
2
Mass per unit volume
3
Disturbance that transfers energy
4
Positive particle in nucleus
6
Nerve cell in the brain
10
Naturally occurring inorganic solid
11
Second lightest element
13
Chemical element in table salt