Which of the following elements exhibits a $+4$ oxidation state?

The chemistry of the actinoid elements is not so smooth as that of the lanthanoids. Justify this statement by giving some examples from the oxidation states of these elements.

Which of the following elements are included in the actinoid series?

The percentage of lanthanides and iron,respectively,in misch metal are

Which general symbol is used to represent lanthanoids?

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ All actinoid elements have a $7s^1$ configuration.
$(b)$ All actinoid elements have a $7s^0$ configuration.
$(c)$ There are no electrons in the $7s$ orbital of actinoids.