Across
1
Smallest unit of an element
3
Substance with pH below 7
5
Blocking of light by a celestial body
8
Group of similar cells
9
Precious yellow metallic element
10
Disturbance that transfers energy
11
Ball of burning gas in space
Down
2
Force that attracts objects together
4
Icy body with a tail near the sun
6
The Red Planet
7
Tissue that contracts for movement
9
Unit of heredity
12
Basic unit of life