Both statement I and statement II are true. The +3 oxidation state of lanthanide is most stable and therefore lanthanide in +4 oxidation state has strong tendency to gain electrons and converted into +3 and therefore act as strong oxidising agent, e.g. Ce4+. ∴CeO2 is used to oxidised alcohol, aldehyde and ketones. Lanthanides in +2 oxidation state has strong tendency to loss electron and converted into +3 oxidation state e.g. Eu+2. ∴ EuSO 4 acts as strong reducing agent.