Across
1
Preserved remains of ancient life
3
Hottest planet in solar system
5
Chemical element in table salt
7
Gas essential for breathing
8
Mass per unit volume
13
Path of a planet around the sun
14
Basic unit of life
Down
2
Group of similar cells
4
Center of an atom or cell
6
Compound containing oxygen
9
Smallest unit of an element
10
Precious yellow metallic element
11
Magnetic metallic element
12
Naturally occurring inorganic solid