Question

Which of the following is most basic?

• A. \( Mn_2O_7 \)
• B. \( MnO_2 \)
• C. \( MnO \)
• D. \( Mn_2O_3 \)

Hint:

Remember: Basicity \(\propto \frac{1}{\text{Oxidation Number}}\). Transition metal oxides in high oxidation states act as Lewis acids.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
For oxides of transition metals, the basicity is inversely proportional to the oxidation state of the metal.
Lower oxidation states lead to ionic character and basic nature, while higher oxidation states lead to covalent character and acidic nature.
Step 2: Detailed Explanation:
Metal oxides in low oxidation states (like \( +2 \)) are basic because the metal can easily donate electron pairs.
As the oxidation state increases to \( +4 \) or higher, the metal-oxygen bond becomes more covalent, making the oxide amphoteric or acidic.
In \( MnO \), Manganese is in its lowest oxidation state (\( +2 \)) among the options, making it the most basic oxide.
Conversely, \( Mn_2O_7 \) (+7) is strongly acidic.
Step 3: Final Answer:
The most basic oxide is \( MnO \).