What is the Oxidation number on IF7?

The oxidation number of iodine in IF7 is +7. This is because fluorine is more electronegative than iodine, so each fluorine atom in the compound carries an oxidation number of -1. Since there are 7 fluorine atoms in IF7, the total charge from fluorine is -7, which means iodine must have an oxidation number of +7 to balance the charge.