D-And F-Block Elements Ques 402

Question: Lanthanoids are

[CBSE PMT 2004]

Options:

A) 14 elements in the sixth period (atomic no. = 58 to 71) that are filling 4f sublevel

B) 14 elements in the seventh period (atomic no. = 58 to 71) that are filling 4f sublevel

C) 14 elements in the sixth period (atomic no. = 90 to 103) that are filling 4f sublevel

D) 14 elements in the seventh period (atomic no. = 90 to 103) that are filling 4f sublevel

Show Answer

Answer:

Correct Answer: A

Solution:

As sixth period can accommodate only 18 element in the table, 14 member of HF series (atomic number 58 ot 71) are separately accommodated in a horizontal row below the periodic table.

These are called as lanthanides.



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