Question

Which metal in following compounds is not present in fractional oxidation state?

• A. $\text{Fe}_3\text{O}_4$
• B. $\text{Mn}_3\text{O}_4$
• C. $\text{Pb}_3\text{O}_4$
• D. $\text{Na}_2\text{S}_4\text{O}_6$

Hint:

Look at the wording! Alkali metals (Group 1) like Na always have $+1$ and Alkaline Earth (Group 2) always have $+2$. They never go fractional.

Answer 1

The Correct Option is D

Step 1: Concept
Fractional oxidation states often appear in mixed oxides or molecules where multiple atoms of the same element have different integer oxidation states, leading to a fractional average.

Step 2: Meaning
In $\text{Fe}_3\text{O}_4$, $\text{Mn}_3\text{O}_4$, and $\text{Pb}_3\text{O}_4$, the metal atoms average to $+8/3$.

Step 3: Analysis
The question asks for the "metal" not present in a fractional state. In $\text{Na}_2\text{S}_4\text{O}_6$ (sodium tetrathionate), the sodium ($Na$) is the metal, and it has a fixed oxidation state of $+1$. While Sulfur ($S$) has a fractional average state of $+2.5$, Sulfur is a non-metal.

Step 4: Conclusion
The alkali metal Sodium always exhibits a stable $+1$ oxidation state in its compounds. Final Answer: (D)