Question

A fluorine ion has nine protons and a charge of -1. how many electrons are in an ion the fluorine. A. 1 B. 9 C. 10 D. 8

Answer 1

10, it has gained and electron which increases the charge, as the -1 indicates 

Answer 2

The neutral Fluorine atom has 9 electrons AND 9 protons. So if the F has a -1 charge, then another electron is added so F will now have 10 electrons. so answer C