Per NCERT §3.6.4, the f-block elements (inner-transition) consist of which TWO series, and their atomic-number ranges are which?
ALanthanoids Ce (Z=58) → Lu (Z=71); Actinoids Th (Z=90) → Lr (Z=103)
BLanthanoids Z=21–30; Actinoids Z=39–48
CLanthanoids Z=1–14; Actinoids Z=15–28
DLanthanoids Z=89–103; Actinoids Z=58–71
Answer & Solution
Correct answer: A. Lanthanoids Ce (Z=58) → Lu (Z=71); Actinoids Th (Z=90) → Lr (Z=103)
Per NCERT §3.6.4, lanthanoids Ce(58)–Lu(71), actinoids Th(90)–Lr(103). General outer config (n−2)f¹⁻¹⁴ (n−1)d⁰⁻¹ ns².
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