Across
1
Ball of burning gas in space
4
Unit of heredity
5
Preserved remains of ancient life
9
The Red Planet
11
Chemical element in table salt
12
Blocking of light by a celestial body
Down
2
Substance with pH above 7
3
Smallest unit of an element
6
Gas form of a liquid
7
Magnetic metallic element
8
Disturbance that transfers energy
10
Tissue that contracts for movement
13
Substance with pH below 7