The number of element from the following that do not belong to lanthanoids is :
Eu, Cm, Er, Tb, Yb and Lu
Eu, Cm, Er, Tb, Yb and Lu
- 3
- 4
- 1
- 5
The Correct Option is C
Approach Solution - 1
The given question requires identification of elements among the given list that do not belong to the lanthanoid series. The lanthanoids, also known as the lanthanides, consist of 15 elements ranging from atomic numbers 57 (Lanthanum, La) to 71 (Lutetium, Lu).
Let's evaluate each element in the list:
- Eu (Europium): Europium is a lanthanoid with an atomic number of 63.
- Cm (Curium): Curium is an actinoid with an atomic number of 96. It does not belong to the lanthanoid series.
- Er (Erbium): Erbium is a lanthanoid with an atomic number of 68.
- Tb (Terbium): Terbium is a lanthanoid with an atomic number of 65.
- Yb (Ytterbium): Ytterbium is a lanthanoid with an atomic number of 70.
- Lu (Lutetium): Lutetium is the last element of the lanthanoid series with an atomic number of 71.
From this evaluation, we can see that the element Cm (Curium) is the only one that does not belong to the lanthanoid series.
Conclusion: The correct answer is option \(1\), as Cm (Curium) is the only element that is not a lanthanoid.
Approach Solution -2
Among the given elements: - Eu (Europium), Er (Erbium), Tb (Terbium), Yb (Ytterbium), and Lu (Lutetium) all belong to the lanthanoid series. Cm (Curium) belongs to the actinide series.
Hence, the number of elements that do not belong to lanthanoids is 1 (Cm).
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