Answer:
C < N < O.
Explanation:
Hello!
In this case, since the electron affinity is a periodic property of elements indicating how likely is for the element to gain one electron, which is also related to the electronegativity, we can notice that fluorine is the most electronegative element or also, the element with the highest electron affinity whereas francium is the least electronegative element.
Therefore, we can infer that the electron affinity or electronegativity, increases from left to right and from bottom to top in the periodic table, it means that among carbon, nitrogen and oxygen, the element with the greatest electron affinity is oxygen, then nitrogen and finally carbon with the least one, thus answer is C < N < O.
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