Find the connections

Group 16 science words into 4 categories of 4. Each group shares a hidden connection.

Puzzle #1
Tap 4 words that you think share a connection, then hit Submit. If correct, the group is revealed. You get 4 mistakes before game over. Groups range from straightforward (๐ŸŸข) to tricky (๐ŸŸฃ). Each puzzle has exactly one correct solution.
Mistakes remaining