Across
1
Particle of light
5
Compound containing oxygen
8
Gas essential for breathing
9
Group of similar cells
11
Our home planet
12
Tectonic landmass section
13
Substance with pH above 7
Down
2
Push or pull on an object
3
Mass per unit volume
4
Reddish electrical conductor
6
Icy body with a tail near the sun
7
Preserved remains of ancient life
10
Force that attracts objects together