Question

Does Oxygen have higher electron affinity than Cl?

Answer 1

Oxygen has a lower electron affinity than Chlorine. We can see that using the Florine to Francium pattern:
As you move upwards and to the left, electron affinity increases. ![https://useruploads.socratic.org/XcHk4Q6JQkGR3hs9D2kO_electron_affinity_trend.png)

We can also use this diagram