Prefixes im and in

Add the correct prefix to these words:

capable mature definite
complete edible
mobile movable precise
passable sincere credible

For each word
1. add the correct prefix
2. What do you notice when you added the prefix? (Are there any rules?)
3. How did you know which prefix to use? How can you check if you are correct?
4. What was the meaning of the root word?
5. What is the meaning of the word with the prefix added?