In context of the lanthanoids, which of the following statements is not correct?
A. There is a gradual decrease in the raii of the members with increasing atomic number in the series.
B. All the member exhibit +3 oxidation state.
C. Because of similar properties the separation of lanthanoids is not easy.
D. Availability of 4f electrons results in the formation of compounds in +4 state for all the m embers of the series.
