which of the following statements are incorrect?
A. All the transition metals except scandium form MO oxides which are iconic
B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc₂O₃ to Mn₂O₇
C. Basic character increases from V₂O₃ to V₂O₄ to V₂O₅
D. V₂O₄ dissolves in acids to give VO salts
E. CrO is basic but Cr₂O₃ is amphoteric
Choose the correct answer from the options given below:

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Answer 1

To determine which statements are incorrect, we need to analyze each one based on the properties of transition metal oxides.

Statement A: "All the transition metals except scandium form MO oxides which are iconic."
- Transition metal oxides often have ionic character; however, their nature can vary between ionic and covalent depending on the specific metal and its oxidation state.
- This statement is correct as oxides of transition metals do tend to have ionic characteristics, especially in their lower oxidation states. Scandium forms Sc₂O₃, which is covalent.
Statement B: "The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc₂O₃ to Mn₂O₇."
- The highest oxidation state is exhibited by manganese in Mn₂O₇ which is +7, the maximum for transition metals.
- This statement is correct as Mn attains its group number oxidation state (+7) in Mn₂O₇.
Statement C: "Basic character increases from V₂O₃ to V₂O₄ to V₂O₅."
- The basic character usually decreases, while acidic character increases as the oxidation state increases in oxides of the same element.
- In fact, V₂O₅ is the most acidic among them. Hence, this statement is incorrect.
Statement D: "V₂O₄ dissolves in acids to give VO salts."
- V₂O₄ is vanadium dioxide, and it usually forms VO₂⁺ ions in acidic solution, not simple VO salts.
- Thus, this statement is incorrect.
Statement E: "CrO is basic but Cr₂O₃ is amphoteric."
- This statement is correct. CrO is a basic oxide, whereas Cr₂O₃ is amphoteric, meaning it can react with both acids and bases.

Conclusion: The incorrect statements are C and D. Therefore, the answer is "C and D only".

Answer 2

To determine which statements are incorrect, we need to analyze each one based on the properties of transition metal oxides.

Statement A: "All the transition metals except scandium form MO oxides which are iconic."
- Transition metal oxides often have ionic character; however, their nature can vary between ionic and covalent depending on the specific metal and its oxidation state.
- This statement is correct as oxides of transition metals do tend to have ionic characteristics, especially in their lower oxidation states. Scandium forms Sc₂O₃, which is covalent.
Statement B: "The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc₂O₃ to Mn₂O₇."
- The highest oxidation state is exhibited by manganese in Mn₂O₇ which is +7, the maximum for transition metals.
- This statement is correct as Mn attains its group number oxidation state (+7) in Mn₂O₇.
Statement C: "Basic character increases from V₂O₃ to V₂O₄ to V₂O₅."
- The basic character usually decreases, while acidic character increases as the oxidation state increases in oxides of the same element.
- In fact, V₂O₅ is the most acidic among them. Hence, this statement is incorrect.
Statement D: "V₂O₄ dissolves in acids to give VO salts."
- V₂O₄ is vanadium dioxide, and it usually forms VO₂⁺ ions in acidic solution, not simple VO salts.
- Thus, this statement is incorrect.
Statement E: "CrO is basic but Cr₂O₃ is amphoteric."
- This statement is correct. CrO is a basic oxide, whereas Cr₂O₃ is amphoteric, meaning it can react with both acids and bases.

Conclusion: The incorrect statements are C and D. Therefore, the answer is "C and D only".

The Correct Option is B

Solution and Explanation

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