Question

Lanthanoid contraction is observed in:

• A. s-block elements
• B. f- block elements
• C. d- block elements
• D. p- block elements

Answer 1

The correct option is C

d- block elements

There is an increase in radii from the first (3) to the second (4) series of the elements but the radii of the third (5) series are virtually the same as those of the corresponding members of the second series. This phenomenon is called Lanthanoids contraction.