Which of the following represents an ion?

a 4he

b Na 2+

c Ca

d Mg

Na2 + (answer B) represent ions.

Explanation

This is because it has a charge of 2+. ion is formed when an atom gain or lose electrons. when an atom lose electrons it form ion which is positively charged. On the other hand when atom gain electrons it forms ion of negatively charged. Na2 + has a charge of 2 + since it loses two electrons.