Which of these would be most likely to gain an electron in order to form a bond with another atom? a. na b. ca c. cl d. ne

So Na (sodium) and Ca (calcium) are metals which form ionic bonds by acting as cations. cations are positively charged since they GIVE AWAY electrons to anions when they bond. So A and B are out.

Ne (neon) is a noble gas which (according to octet rule) has 8 electrons already in it's outer orbit. So since that is the most stable form for an atom, neon would not give or take any electrons and destabilize itself.

Cl (chlorine) is a halogen which forms covalent bonds by GAINING one electron to stabilize itself. Cl only has 7 electrons in its outer orbit so it wants 1 more to reach 8, the stable state. So your answer is C. Cl