Explain
(i) The atomic size of cerium and promethium is quite similar.
(ii) Magnetic behaviour of lanthanoids.
(iii) Shielding power of 4f -electrons, is quite poor.

The atomic size of cerium and promethium is. quite close, because

Compare the chemistry of actinoids with that of lanthanoids with special reference to- (i) electronic configuration (ii) oxidation state (iii) atomic and ionic sizes (iv) chemical reactivity

Compare the chemistry of actinoids with that of lanthanoids with special reference to- (i) electronic configuration (ii) atomic and ionic radii (iii) oxidation states.