Answer:
Fluorine (F) would be least likely to form a cation
Explanation:
A cation is a positively charged atom (or molecule) which has lost electron (or electrons). Electropositive elements show a greater propensity to lose electrons and form cations. These are usually metals that are present on the left of the periodic table.
Electropositivity or the tendency to lose electrons and form cations increases on going down a group and decreases across a period. In the given examples:
Potassium, K is an alkali metal and will lose electrons readily to form a cation
Nitrogen (N), Fluorine (F) and chlorine (Cl) are all non metals which prefer to accept electrons and form anions instead. Among the three, F is the most electronegative i.e. it will prefer to accept electrons and form F- rather than F+.
