Across
1
Ball of burning gas in space
4
Substance with pH below 7
5
Molten rock beneath Earth surface
7
Center of an atom or cell
8
Positive particle in nucleus
Down
2
Smallest unit of an element
3
The Red Planet
5
Measure of matter in an object
6
Force that attracts objects together
9
Unit of heredity
10
Push or pull on an object