Which of the following is a lanthanoid element?

What is lanthanoid contraction? What are the consequences of lanthanoid contraction?

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ The symbol for Lanthanum is $La$.
$(b)$ The name of the element $Lu$ is Lanthanum.
$(c)$ The electronic configuration of $La^{3+}$ and $Ce^{4+}$ contains $4f^0$.

What does lanthanoid contraction result in?

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

Discuss the trends in oxidation states shown by actinoids.