NEET 2023 Chemistry Oxidation States Multiple Correct Question

To analyze the question regarding the statements about transition metals, we need to evaluate each statement carefully to determine which are incorrect.

Statement Analysis

A. All the transition metals except scandium form MO oxides which are ionic.

• This statement is incorrect. While many transition metal oxides (MO) can exhibit ionic character, especially in lower oxidation states, not all of them are purely ionic. For instance, CrO and TiO display significant covalent character, particularly as we move to higher oxidation states. Therefore, the characterization of all transition metal oxides as ionic is flawed.

B. The highest oxidation number corresponding to the group number in transition metal oxides is attained in Sc2O3 to Mn2O7.

• This statement is also incorrect. The highest oxidation states do not necessarily correspond to the group number. For example, Mn can achieve a +7 oxidation state in MnO₄⁻ (permanganate), which is not directly related to its group number. Additionally, not all transition metals reach their maximum oxidation states in oxides straightforwardly based on their group number.

C. Basic character increases from V2O3 to V2O4 to V2O5.

• This statement is incorrect. The basicity of oxides generally decreases as the oxidation state of the metal increases. Vanadium (V) in V2O3 has a lower oxidation state than in V2O5, and hence V2O3 is more basic than V2O5. Therefore, we observe that the basic character does not increase but rather decreases from V2O3 to V2O4 to V2O5.

D. V2O4 dissolves in acids to give VO4^3- salts.

• This statement is incorrect. Vanadium (IV) in V2O4 typically forms vanadyl ions (VO²⁺) when dissolved in acids, leading to the formation of salts like VOCl₂, rather than VO₄³⁻. Therefore, the statement is misleading about the soluble species formed.

E. CrO is basic but Cr2O3 is amphoteric.

• This statement is correct. CrO (chromium(II) oxide) is basic and reacts with acids. In contrast, Cr2O3 (chromium(III) oxide) behaves amphoterically, meaning it can react with both acids and bases.

Summary of Incorrect Statements

• Incorrect Statements: A, B, C, D
• Correct Statements: E

Conclusion

Based on the evaluation:

• The incorrect statements are A, B, C, and

D. - Therefore, the correct answer should reflect that statements B and C are incorrect, not as initially stated.

Final Correct Answer

Considering all statements and their evaluations, the correct conclusion is that statements A, B, C, and D are incorrect while E is correct.

Thus, the correct answer would imply that both B and C are indeed incorrect. Given the options, the most suitable answer based on incorrect statements is A) B and D only, as it reflects inaccuracies in statements B and D specifically.

Conceptual Clarification

In transition metals, oxidation states can vary significantly, and the properties of their oxides can differ based on the metal's oxidation state. The nature (basic, acidic, amphoteric) of these oxides is fundamentally linked to their oxidation state and the type of bonding character (ionic vs. covalent) exhibited.