Q104 / 200 · MHT CET - Medical 2026 (23 April Shift 2) · Chemistry
What is the change in oxidation number of S in the following reaction?
$\text{SO}_2 + 2\text{H}_2\text{S} \rightarrow 3\text{S} + 2\text{H}_2\text{O}$
$\text{SO}_2 + 2\text{H}_2\text{S} \rightarrow 3\text{S} + 2\text{H}_2\text{O}$
- A$-2$ to $1$
- Correct answerB$-2$ to $0$
- C$-2$ to $3$
- D$-2$ to $-3$
Solution
In $H_2S$, let the oxidation number of S be $x$.
Assuming the typical oxidation number of H is $+1$:
$2(+1) + x = 0$
$x = -2$
In the products, sulfur is formed in its standard elemental state as S.
The oxidation number of any element in its free uncombined state is $0$.
Thus, the oxidation number of S changes from $-2$ to $0$.
Answer: $-2$ to $0$
Assuming the typical oxidation number of H is $+1$:
$2(+1) + x = 0$
$x = -2$
In the products, sulfur is formed in its standard elemental state as S.
The oxidation number of any element in its free uncombined state is $0$.
Thus, the oxidation number of S changes from $-2$ to $0$.
Answer: $-2$ to $0$
Hence, the correct answer is option: 'B'.