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

Transuranium elements are

Which of the following statements regarding Lanthanides is false?

If the ionic radius of $_{57}La^{3+}$ is $1.06 \ \mathring{A}$,then the ionic radius of $_{71}Lu^{3+}$ will be approximately close to which of the following values in $\mathring{A}$?

The common oxidation state of the elements of the lanthanoid series is .....

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