When na and cl combine to form a compound, which atom(s) will become a cation?
na only
cl only
both na and cl
neither na nor cl

Na only.

Explanation:

When sodium (Na) and chlorine (Cl) combines to form a compound, sodium atom will become a cation(positively charged ion).

Both elements are known to be unstable due to their incomplete outermost shell. Chlorine has 7 valence electron in its outermost shell while sodium has 1 valence electron in its outermost shell. Sodium will donate its lone pair of electron to chlorine through covalent bonding to complete the outermost shell of chlorine thereby forming a NaCl compound (sodium chloride).

Chlorine being an acceptor will become a negatively charged ion(anion) while sodium being the donor will become positively charged ion (cation)