Across
1
Magnetic metallic element
3
Ball of burning gas in space
5
Biological catalyst
7
Gas essential for breathing
10
Basic unit of life
11
Chemical element in table salt
12
Unit of energy
13
Mass per unit volume
Down
2
Substance with pH below 7
4
Unit of force
6
Hottest planet in solar system
8
Naturally occurring inorganic solid
9
Tissue that contracts for movement