Explain giving reasons :
(i) Transition metals and their compounds generally exhibit a paramagnetic behaviour.
(ii) The chemistry of actinoids is not so smooth as that of lanthanoids.

Explanation

(i) The transition elements involve the partial filling of d-subshells. Most of the transition metal ions have unpaired electrons in d-subshell (from `d^(1 to 10))` and therefore they give rise to paramegnetic character.
(ii) In lanthanoids, the differentiating electron enters in 4f-orbital but in actinoids the differentiating electron enters in 5f-orbital which makes its chemistry slightly typical.