Lanthanoids are...

Lanthanoids are

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

14 elements in the seventh period (atomic no = 90 to 103) that are filling 5f sublevel

14 elements in the 6th period (atomic no = 58 to 71) that are filling the 4f sublevel

14 elements in the 7th period (atomic no = 50 to 71) that are filling the 4f sublevel

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The correct Answer is:

Lanthanons or lanthanides are 14 elements `(Z = 58 to 71)` of group '3' and sixth period. They are characterized by the filling up the antepenulimate 4f energy l,evels. Actually, they are placed below the periodic table in horizontal row as lanthanide series.

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Lanthanoid are:

`14` elements in the sixth period (`at.no .90` to `103`) that have4f-subshell

`14` elements in the seventh period `(at.no .90` to `103 )` that have `5f-`subshell

`14` elements in the sixth period (`at.no .58` to `71`) that have4f-subshell

`14` elements in the seventh period (`at.no .58` to `71`) that have4f-subshell

A: Lanthanoids have +3 as most common oxidation state. R: Electrons of 4f in lanthanoids rarely participate

If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)

If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)

If Assertion is true statement but Reason is false, then mark (3)

Statement A is true ,Statement B is false

Lanthanoid from series is

La to Lu

Th to Lr

Ce to Lu

Ac to Lr