Question

The charges for four ions are sodium (Na) +1, calcium (Ca) +2, fluorine (F) –1, and sulfur (S) –2. Which would be an ionic bond that could form from any of these ions?
A.NaCa2
B.Na2S
C.CaF
D.FS

Answer 1

Answer: B. $Na_2S$

Explanation: An ionic bond is formed when an element completely transfers its valence electron to another element. Ionic bond is formed between a metal and an non-metal.

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.  

Here $Na$ is having an oxidation state of +1 and sulfur has an oxidation state of -2. Thus they combine to form neutral $Na_2S$.

$Ca$ is having an oxidation state of +2 and fluorine has an oxidation state of -1. Thus they combine to form neutral $CaF_2$. and not $CaF$.

Answer 2

The correct answer would be B. It is the compound Na2S that forms an ionic bond from the given ion above. From the choices, it is the only compound that exist and is available. Metals cannot react with another metal as well as nonmetal to nonmetal.