Across
1
Amplified beam of light
4
Disturbance that transfers energy
5
Icy body with a tail near the sun
8
Substance with pH below 7
10
Measure of matter in an object
Down
2
Nerve cell in the brain
3
Substance with pH above 7
6
Force that attracts objects together
7
Smallest unit of an element
9
Group of similar cells