Which lanthanoid from the following may exhibit $+4$ oxidation state with $f^{0}$ configuration?

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 $4f^0$.

State the consequences of lanthanoid contraction. Explain the formation of coloured ions by lanthanoids.

Which of the following properties decreases on moving from $Ce$ to $Lu$?

Identify the element having the smallest ionic size in the $+3$ state from the following.

Which of the following elements is not an actinoid?