Across
1
Measure of matter in an object
3
Naturally occurring inorganic solid
6
Compound containing oxygen
7
Basic unit of life
8
Precious yellow metallic element
9
Smallest unit of an element
Down
2
Second lightest element
3
Molten rock beneath Earth surface
4
Unit of energy
5
Substance with pH below 7
7
Icy body with a tail near the sun