Chemistry · Periodicity of Elements and Periodic Properties
JEE Main 2025 — 8 April, Evening Shift — Question 14
The atomic number of the element from the following with lowest ionisation enthalpy is
- Option A:
35
- Option B:
19
- Option C:
32
- Option D:Correct
87
Answer: D
Step-by-step solution
| Atomic No. | Period No. | Group No. |
|---|---|---|
| 35 | 4 | 17 |
| 19 | 4 | 1 |
| 32 | 4 | 14 |
| 87 | 6 | 1 |
First ionisation energy of an element generally decreases down the group and increases from left to right
along a period. Therefore, element having atomic number 87 has the lowest first ionisation energy.
Answer key and solution verified before publishing.
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- Exam
- JEE Main 2025
- Subject
- Chemistry
- Chapter
- Periodicity of Elements and Periodic Properties
- Topic
- Periodicity in Chemical Properties (Ionization Energy, Electron Affinity, Electronegativity)