(A)14 elements in the sixth period (atomic no. = 90 to 103) that are filling 4f-sublevel
(B)14 elements in the seventh period (atomic no. = 90 to 103) that are filling 5f-sublevel
(C)14 elements in the sixth period (atomic no. = 58 to 71) that are filling 4f-sublevelCorrect
(D)14 elements in the seventh period (atomic no. = 58 to 71) that are filling 4f-sublevel
Answer: (C)
Solution
The lanthanoids are the 14 elements with atomic numbers 58 (Ce) to 71 (Lu), located in period 6 of the periodic table, in which the subshell is progressively filled.
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