Answer:
[tex]Ca(g)+e--->Ca^{-}(g)[/tex]
Explanation:
The electron affinity is the energy released in addition of one electron to an isolated gaseous atom (for neutral atom).
Thus the atom in the equation should be gaseous
The reaction should show addition of electron in the atom
After addition of electron the product will be a negative gaseous ion (mono negative).
Thus the equation will be:
[tex]Ca(g)+e--->Ca^{-}(g)[/tex]
