JEE Main 202622 JanuaryMorning Shift
- Exam
- JEE Main
- Year
- 2026
- Date
- 22 January
- Shift
- Morning Shift
- Subject
- Chemistry
- Chapter
- p Block Elements (Group 15, 16, 17 & 18)
JEE Main 2026 · 22 January · Morning Shift · Chemistry · p Block Elements (Group 15, 16, 17 & 18)
A ' p '-block element (E) and hydrogen form a binary cation (EH_ x...
A ' p '-block element and hydrogen form a binary cation \left(\mathrm{EH}_{\mathrm{x}}\right)^{+}\mathrm{EH}_{3}\mathrm{K}_{2} \mathrm{HgI}_{4}\left(\mathrm{kJ} \mathrm{mol}^{-1}\right) for first element each from group 13, 14, 15 and 16. Identify the correct first ionisation enthalpy value for element E.
Options
- A1312
- B1402
- C1086
- D801
Correct answer
B. 1402
Step-by-step solution
The p-block element E forms a binary cation with hydrogen and produces a basic mercury(II) amido-iodide precipitate with in alkaline medium.
This behavior is characteristic of ammonia (NH₃), which forms the ammonium ion and reacts with Nessler's reagent () to form a characteristic brown/yellow precipitate.
Therefore, E is Nitrogen (N), a Group 15 p-block element with electronic configuration .
Nitrogen has a notably high first ionization enthalpy compared to other group 15 elements due to:
Small atomic radius
High effective nuclear charge
Stable half-filled p³ subshell configuration
The first ionization enthalpy of nitrogen is 1402 kJ/mol.
This behavior is characteristic of ammonia (NH₃), which forms the ammonium ion and reacts with Nessler's reagent () to form a characteristic brown/yellow precipitate.
Therefore, E is Nitrogen (N), a Group 15 p-block element with electronic configuration .
Nitrogen has a notably high first ionization enthalpy compared to other group 15 elements due to:
Small atomic radius
High effective nuclear charge
Stable half-filled p³ subshell configuration
The first ionization enthalpy of nitrogen is 1402 kJ/mol.