When a voltaic cell changes to begin operating as an electrolytic cell,

A. the positive electrode changes from being the cathode to being the anode.
B. the negative electrode becomes both the anode and the cathode.
C. the positive electrode changes from being the site of oxidation to being the site of reduction.
D. the negative electrode becomes the site of both oxidation and reduction.

the energy to form plasma comes from heat or electricity in the atmosphere!

sunny~ ☺

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.