The first ionization enthalpy of carbon is greater than that of boron, whereas the reverse is true for second ionization enthalpy. Explain.

Answer

Carbon has higher `IE_(1)` because of smaller atomic size and greater `Z_(eff)`. Removal of second electron from stabel `1s^(2)2s^(2)` configuration in case of `B^(+)` requires greater energy . So, `B` has greater `IE_(2)`.

Explanation

The first ionization enthalpy of carbon is greater than that of boron, whereas the reverse is true for second ionization enthalpy. Explain.
Carbon has higher `IE_(1)` because of smaller atomic size and greater `Z_(eff)`. Removal of second electron from stable `1s^(2)2s^(2)` configuration in case of `B^(+)` requires greater energy. So, `B` has greater `IE_(2)`.