Name the member of the lanthanoid series which is well known to exhibit $+4$ oxidation state.

Which of the following transition metal is present in misch metal?

Determine the correct $(T)$ and incorrect $(F)$ statements from the following:
$(a)$ $Lu^{3+}$ and $Yb^{2+}$ are not paramagnetic.
$(b)$ Sheets are made from mischmetal.
$(c)$ Pipes are made from mischmetal.

Which one of the lanthanoids given below is the most stable in divalent form?

Observe the following $f$-block elements: $Eu (Z=63)$; $Pu (Z=94)$; $Cf (Z=98)$; $Sm (Z=62)$; $Gd (Z=64)$; $Cm (Z=96)$. How many of the above have half-filled $f$-orbitals in their ground state?

Cerium $(Z = 58)$ is an important member of the lanthanoids. Which of the following statements about cerium is incorrect?