What is the correct order of electron affinity for $B, C, N$,and $O$?

Which of the following processes involves absorption of energy?

Which of the following statements is correct?

Consider the following conversions:
$(i) \ O_{(g)} + e^- \to O^{-}_{(g)} ; \Delta H_1$
$(ii) \ F_{(g)} + e^- \to F^{-}_{(g)} ; \Delta H_2$
$(iii) \ Cl_{(g)} + e^- \to Cl^{-}_{(g)} ; \Delta H_3$
$(iv) \ Na_{(g)} \to Na^{+}_{(g)} + e^- ; \Delta H_4$
Which of the following statements is incorrect?

Select the process in which the least enthalpy change is associated:

When the first electron gain enthalpy $(\Delta _{eg}H)$ of oxygen is $-141 \ kJ/mol,$ its second electron gain enthalpy is