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Q21
(CDS-I/2026)
Science & Technology › Basic Science (Physics, Chemistry, Biology)
Match List-I with List-II and select the answer using the codes given below the Lists: List-I (Symbol of Element) A. Sm B. Cs C. Os D. Np List-II (Group of Element) 1. Transition Elements 2. Alkali Metals 3. Actinoid Elements 4. Lanthanoid Elements
Result
Your answer:
—
·
Correct:
A
Explanation
The correct matching of the elements with their respective groups in the periodic table is as follows:
- Sm (Samarium): Atomic number 62, it belongs to the Lanthanoid series (f-block elements).
- Cs (Caesium): Atomic number 55, it is a highly reactive Alkali Metal located in Group 1.
- Os (Osmium): Atomic number 76, it is a d-block element classified as a Transition Element; it is also the densest naturally occurring element.
- Np (Neptunium): Atomic number 93, it is the first transuranic element and belongs to the Actinoid series (f-block elements).
Matching these pairs (A-4, B-2, C-1, D-3) leads to the correct sequence 4 2 1 3, which is Option A.
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