Science Brain Teaser

Public|
6
3
8
5
2
9
7
1
4

Across

1

The Red Planet

4

Smallest unit of an element

5

Our home planet

7

Nerve cell in the brain

9

Preserved remains of ancient life

Down

2

Form of thermal energy

3

Mass per unit volume

6

Basic unit of life

8

Curved glass that refracts light