Which one of the following statements related to lanthanons is incorrect?

1. ${\text{Ce}}^{4+}$ is a good oxidizing agent as it tends to return to the more stable $+3$ state.2. ${\text{Eu}}^{2+}$ exists (attains $f^7$ configuration).3. Lanthanide contraction causes ionic radius to decrease; thus, the covalent character of hydroxides increases and basicity decreases.4. Incorrect statement: Lanthanons are reactive metals, but their reactivity is comparable to magnesium/aluminum. They are not "much more" reactive than aluminum in a general sense; aluminum is already quite reactive but forms a protective oxide layer.