Across
1
Naturally occurring inorganic solid
5
Element found in all living things
6
Gas essential for breathing
7
Nerve cell in the brain
8
Group of similar cells
Down
2
Compound containing oxygen
3
Substance with pH below 7
4
Blocking of light by a celestial body
5
Basic unit of life
9
Force that attracts objects together
10
Infectious microscopic agent
11
Unit of force