JEE Main 202624 JanuaryEvening Shift
- Exam
- JEE Main
- Year
- 2026
- Date
- 24 January
- Shift
- Evening Shift
- Subject
- Chemistry
- Chapter
- Classification of Elements and Periodicity in Properties
JEE Main 2026 · 24 January · Evening Shift · Chemistry · Classification of Elements and Periodicity in Properties
The correct order of C, N, O and F in terms of second ionisation...
The correct order of and F in terms of second ionisation potential is
Options
- A
- B
- C
- D
Correct answer
A.
Step-by-step solution
Second ionization potential (I₂) is the energy to remove the second electron.
After removing the first electron: C⁺ has 2p¹, N⁺ has 2p², O⁺ has 2p³ (half-filled, stable), F⁺ has 2p⁴.
C has lowest I₂ as 2p electrons are least tightly bound with lowest nuclear charge.
N has slightly higher I₂ than C due to increased nuclear charge.
F has highest I₂ due to highest effective nuclear charge.
O⁺ with half-filled 2p is relatively stable, making I₂ of O intermediate.
Order:
After removing the first electron: C⁺ has 2p¹, N⁺ has 2p², O⁺ has 2p³ (half-filled, stable), F⁺ has 2p⁴.
C has lowest I₂ as 2p electrons are least tightly bound with lowest nuclear charge.
N has slightly higher I₂ than C due to increased nuclear charge.
F has highest I₂ due to highest effective nuclear charge.
O⁺ with half-filled 2p is relatively stable, making I₂ of O intermediate.
Order: