Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R . Assertion A : The first ionization enthalpy of O is lower than that of N and F. Reason R : The loss of an electron from O leads to stable half-filled p orbital. In light of the above statements, choose the most appropriate answer from the options given below:

Step-by-step solution

The electronic configuration of N is 1s^2 2s^2 2p^3 . The electronic configuration of O is 1s^2 2s^2 2p^4 . The electronic configuration of F is 1s^2 2s^2 2p^5 . Generally, the first ionization enthalpy increases across a period due to an increase in effective nuclear charge. Therefore, the ionization enthalpy of F is higher than that of O . However, N has a stable half-filled 2p^3 configuration, which makes it difficult to remove an electron, resulting in a higher ionization enthalpy than O . For O , the loss of o