Answer
+3
Work Step by Step
Recall that the sum of all of the oxidation numbers must be -3 in this molecule. We know that the oxidation number of fluorine is -1. Thus, the oxidation number of Mn must be +3.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.