Ques. 1JEE Main 2025, 23 January (Morning Shift)
The element that does not belong to the same period of the remaining elements (modern periodic table) is:
- Platinum
- Osmium
- Iridium
- Palladium
Answer
(4) Palladium
Solution
Concept: period = highest principal quantum number n.
Pt [Xe] 4f14 5d9 6s1, Os [Xe] 4f14 5d6 6s2, Ir [Xe] 4f14 5d7 6s2 ⇒ n = 6 (6th period)
Pd [Kr] 4d10 ⇒ 5th period ⇒ odd one out.
Answer: (4)