For the second period elements the correct increasing order of first ionization enthalpy is

Question : For the second period elements the correct increasing order of first ionization enthalpy is :

(1) Li <  Be < B < C < N < O< F <  Ne

(2) Li < B < Be < C< O < N < F <  Ne

(3) Li < B < Be < C < N < O < F <  Ne

(4) Li < Be < B < C< O < N < F  < Ne

Answer : from all above options the correct answer is “(2) Li < B < Be < C< O < N < F <  Ne ” and the reason behind this answer is given below –

The effective nuclear charge (Zeff) increases in a period, hence IE increases. Hence, the correct order of increasing ionization energy is Li < B < Be < C < O < N < F < Ne.

Exception :

(i) Be > B. Be has fully-filled ns orbitals and hence higher IE value.
(ii) N >O. N has half-filled electronic configuration and hence higher IE value.
Answer (2)
Answer explanation : as we know that ionization enthalpy is the energy quantity which is need to remove an electron from any atom. and the first ionization enthalpy is the energy which is required to remove first electron from the atom. when effective nuclear charge increases in a period then ionization enthalpy (IE) increases but sometimes some Exceptions can be seen in some cases , after keep in mind (considering) all things the correct answer is “(2) Li < B < Be < C< O < N < F <  Ne” for this question as per question requirement.