Across
1
Gas essential for breathing
3
Measure of matter in an object
4
Our home planet
6
Magnetic metallic element
9
Force that attracts objects together
11
Unit of electric potential
12
Fourth state of matter
Down
2
Group of similar cells
5
Preserved remains of ancient life
7
Chemical element in table salt
8
Compound containing oxygen
10
Substance with pH below 7