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Which one of the following sequences is NOT arranged correctly according to the property mentioned alongside it?

1. Al2O3 < SiO2 < P2O5 < SO3 (order of increasing acidic strength)
2. Al3+ < Mg2+ < Na+ < F- (order of increasing ionic size)
3. B < C < N < O (order of increasing first ionization energy)
4. I < Br < F < Cl (order of increasing electron affinity)

Correct answer: B < C < N < O (order of increasing first ionization energy)

Solution

Nitrogen's half-filled 2p³ configuration gives it extra stability, making IE1(N) > IE1(O). The stated order B < C < N < O incorrectly places N before O; the actual order is B < C < O < N, so this option is wrong.

Related JEE Advanced Chemistry questions

• Which statement accurately describes the trend in chemical reactivity of alkali metals and halogens as their atomic number increases within the group?
• The process of converting O(g) into O²⁻(g) requires 603 kJ mol⁻¹ of energy. If the first electron affinity of O(g) is -141 kJ mol⁻¹, what is the value of the second electron affinity of oxygen?
• The sequence of increasing van der Waals radii for the elements O, N, Cl, F, and Ne is:
• Which of these sequences correctly represents the trend in electron affinity?
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