Question

Which of the following transitions involves maximum amount of energy?

• A. \( M^- (g) \rightarrow M(g) \)
• B. \( M^- (g) \rightarrow M^+ (g) \)
• C. \( M^+ (g) \rightarrow M^{2+} (g) \)
• D. \( M^{2+} (g) \rightarrow M^{3+} (g) \)

Hint:

Transitions involving higher oxidation states, like \( M^{2+} \rightarrow M^{3+} \), require more energy than transitions involving smaller charge differences.

Answer 1

The Correct Option is D

Step 1: Understanding the energy transitions.
The energy required for a transition depends on the charge difference between the ions and the ionization energy. The higher the charge on the ion, the more energy is required to change its oxidation state.

Step 2: Explanation of the options.
- (1) \( M^- (g) \rightarrow M(g) \): This transition involves the removal of an electron, which requires energy, but the change in oxidation state is minimal.
- (2) \( M^- (g) \rightarrow M^+ (g) \): This transition involves the removal of one electron, which requires energy but is not as high as the removal of two electrons.
- (3) \( M^+ (g) \rightarrow M^{2+} (g) \): This transition involves the removal of one electron, but the charge is still relatively low compared to a \( 3+ \) ion.
- (4) \( M^{2+} (g) \rightarrow M^{3+} (g) \): This transition requires the removal of an electron from a \( 2+ \) ion to form a \( 3+ \) ion, which involves a large amount of energy due to the higher charge.

Step 3: Conclusion.
The correct answer is (4) \( M^{2+} (g) \rightarrow M^{3+} (g) \), as it involves the highest charge difference and thus the maximum energy.