JEE Main · 2024 · 04 Apr 2024 · Shift 1 · Classification of Elements and Periodicity

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The correct order of first ionization enthalpy values of the following elements is :
(A) O
(B) N
(C) Be
(D) F
(E) B

Choose the correct answer from the options given below :

(A)B < D < C < E < A
(B)E < C < A < B < D✓ Correct
(C)C < E < A < B < D
(D)A < B < D < C < E

Answer: (B)

Solution

First ionization enthalpy generally rises across a period, with dips where a stable configuration is broken. Across Li–Ne:

B < Be < C < O < N < F .

(B lies below Be because removing a

2 p^{1}

electron is easier than a filled

2 s^{2}

; O lies below N because N has a stable half-filled

2 p^{3}

.)
With A=O, B=N, C=Be, D=F, E=B this reads

E < C < A < B < D .

Option B.

JEE Main · 2024 · 04 Apr 2024 · Shift 1 · Single correct option

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