Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ Mischmetal contains lanthanoids and iron.
$(b)$ The symbol for Cerium is $Cs$.
$(c)$ The symbol for Cerium is $Ce$.

Discuss the trends in oxidation states shown by actinoids.

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

Use Hund's rule to derive the electronic configuration of $Ce^{3+}$ ion and calculate its magnetic moment on the basis of 'spin-only' formula.

Which of the following elements belongs to the actinoids?

Identify all the correct statements for Lanthanide contraction.
$(A)$ The covalent properties of the Lanthanide metal hydroxides increase from $La$ to $Lu$.
$(B)$ The chemical reactivity decreases from $La$ to $Lu$.
$(C)$ $La(OH)_3$ is more basic than $Lu(OH)_3$.
$(D)$ $Zr$ and $Hf$ have about the same radius.
$(E)$ Separation of Lanthanides from one another is easy.