Question

Which of the following is/are exothermic?

I: Electron affinity of F

II: Electron affinity of Ne

III: Electron affinity of O−

Answer is only I. , please explain why it is correct and others are not

Answer 1

exothermic reactions are which relese heat. so basically the question is which will release heat upon accepting an electron. so the most electronegative element will release heat.

1. F is very electronegative atom so it will release heat upon accepting an electron because it will gain noble gas configuration after accepting one electron.

2. Ne is alreday having noble gas configuration so it dont need any electron so it wont realease any heat upon accepting a electron.

3.O- would also get noble gas configuration upon accepting an electron but it has already one excess electron so that would rippel the incoming elctron so it also wont release energy.

so answer is F, Flourine.