Across
1
Measure of matter in an object
3
Substance with pH below 7
5
Biological catalyst
7
Tissue that contracts for movement
8
Path of a planet around the sun
10
Push or pull on an object
Down
2
Icy body with a tail near the sun
4
Chemical element in table salt
6
Positive particle in nucleus
9
Group of similar cells
11
Gas essential for breathing