Q50 / 150 · MHT CET 2026 (19 April Shift 2) · Chemistry
Which from following is NOT an inner transition element ?
- Correct answerA$\text{Rf}$
- B$\text{Ac}$
- C$\text{Lu}$
- D$\text{Ho}$
Solution
Inner transition elements are the f-block elements, which include the lanthanides (atomic numbers $58$ to $71$) and actinides (atomic numbers $90$ to $103$). Sometimes, Lanthanum ($Z=57$) and Actinium ($Z=89$) are also studied along with them due to their similar properties.
$\text{Ho}$ (Holmium, $Z=67$) and $\text{Lu}$ (Lutetium, $Z=71$) belong to the lanthanide series.
$\text{Ac}$ (Actinium, $Z=89$) is the prototype of the actinide series.
$\text{Rf}$ (Rutherfordium, $Z=104$) is a transactinide element. It belongs to Group $4$ and Period $7$ of the periodic table, making it a d-block (transition) element, not an inner transition element.
Answer: $\text{Rf}$
$\text{Ho}$ (Holmium, $Z=67$) and $\text{Lu}$ (Lutetium, $Z=71$) belong to the lanthanide series.
$\text{Ac}$ (Actinium, $Z=89$) is the prototype of the actinide series.
$\text{Rf}$ (Rutherfordium, $Z=104$) is a transactinide element. It belongs to Group $4$ and Period $7$ of the periodic table, making it a d-block (transition) element, not an inner transition element.
Answer: $\text{Rf}$
Hence, the correct answer is option: 'A'.