Which of the following statements are incorrect? A. All the transition metals except scandium form MO oxides which are ionic. B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in $Sc_2O_3$ to $Mn_2O_7$. C. Basic character increases from $V_2O_3$ to $V_2O_4$ to $V_2O_5$. D. $V_2O_4$ dissolves in acids to give $VO_4^{3-}$. E. CrO is basic, but $Cr_2O_3$ is amphoteric. Choose the correct answer from the options given below:

According to the properties of transition metal oxides :

1. Statement A is correct: All transition metals except scandium form MO oxides which are ionic.
2. Statement B is correct: The highest oxidation number in oxides coincides with the group number and is attained in $Sc_2O_3$ to $Mn_2O_7$.
3. Statement C is incorrect: In vanadium, there is a gradual change from the basic $V_2O_3$ to less basic $V_2O_4$ and to amphoteric $V_2O_5$. Thus, the basic character decreases, not increases.
4. Statement D is incorrect: $V_2O_4$ dissolves in acids to give $VO^{2+}$ salts, not $VO_4^{3-}$.
5. Statement E is correct: The well-characterised CrO is basic, but $Cr_2O_3$ is amphoteric.

Therefore, the incorrect statements are C and D.