Fluorine atom has gained an electron and undergone reduction because when an atom gains electron it reduced itself thus acting as an oxidant to oxidize another atom .
For exam sodium fluoride NaF is a salt when sodium fluoride undergo breakdown at that time the fluoride atom gains an electron and is converted to F- anion by the process called reduction .
Heated copper metal reacts with oxygen to form the black copper oxide. The copper oxide can then react with the hydrogen gas to form the copper metal and water.
