To solve this problem, we need to analyze each statement to determine which are incorrect.$\newline$Statement A: "All the transition metals except scandium form MO oxides which are ionic."$\newline$• This statement is incorrect because not all transition metal oxides are purely ionic. Some have covalent character.$\newline$Statement B: "The highest oxidation number corresponding to the group number in transition metal oxides is attained in $Sc_2O_3$ to $Mn_2O_7. \newline$• This statement is correct. Transition metals from Sc to Mn show the highest oxidation states corresponding to their group numbers in their oxides.$\newline$Statement C: "Basic character increases from $V_2O_5$ to $V_2O_3. \newline$• This statement is correct. As the oxidation state decreases, the basic character of the oxide increases.$\newline$Statement D: " $V_2O_5$ dissolves in acids to give $VO_4^{3-}$ salts."$\newline$• This statement is incorrect. $V_2O_5$ is an acidic oxide and dissolves in bases, not acids, to form vanadate ions.$\newline$Statement E: "CrO is basic but $Cr_2O_3$ is amphoteric."$\newline$• This statement is correct. CrO is basic, while $Cr_2O_3$ exhibits amphoteric behavior.$\newline$Analyzing the options:$\newline$• Option 1: A and E only. This is incorrect because E is correct.$\newline$• Option 2: B and D only. This is incorrect because B is correct.$\newline$• Option 3: C and D only. This is correct because D is incorrect.$\newline$• Option 4: B and C only. This is incorrect because both B and C are correct.$\newline$Therefore, the correct option is Option 3, which corresponds to statements C and D being incorrect.