Q95 / 240 · KCET 2026 · Chemistry
Given below are two statements.
Statement-I: In $\text{H}_2\text{O}_2$, each oxygen atom is assigned an oxidation number of $-1$, in $\text{RbO}_2$ each oxygen atom is assigned an oxidation number of $-\dfrac{1}{2}$.
Statement-II: Representation of $\text{HAuCl}_4$ and $\text{MnO}_2$ in stock notation is $\text{HAu(III)Cl}_4$ and $\text{Mn(II)O}_2$, respectively.
Examine the above statements and choose the correct answer.
Statement-I: In $\text{H}_2\text{O}_2$, each oxygen atom is assigned an oxidation number of $-1$, in $\text{RbO}_2$ each oxygen atom is assigned an oxidation number of $-\dfrac{1}{2}$.
Statement-II: Representation of $\text{HAuCl}_4$ and $\text{MnO}_2$ in stock notation is $\text{HAu(III)Cl}_4$ and $\text{Mn(II)O}_2$, respectively.
Examine the above statements and choose the correct answer.
- ABoth Statement I and Statement II are correct
- BBoth Statement I and Statement II are incorrect
- Correct answerCStatement I is correct but Statement II is incorrect
- DStatement I is incorrect but Statement II is correct
Solution
In $\text{H}_2\text{O}_2$, the oxidation state of hydrogen is $+1$. Let the oxidation state of oxygen be $x$.
$2(+1) + 2x = 0 \Rightarrow x = -1$
In $\text{RbO}_2$, rubidium is an alkali metal with an oxidation state of $+1$. Let the oxidation state of oxygen be $y$.
$+1 + 2y = 0 \Rightarrow y = -\dfrac{1}{2}$
Thus, Statement-I is correct.
In $\text{HAuCl}_4$, the oxidation state of Au is $+3$. Its Stock notation is $\text{HAu(III)Cl}_4$.
In $\text{MnO}_2$, the oxidation state of Mn is $+4$. Its Stock notation is $\text{Mn(IV)O}_2$, not $\text{Mn(II)O}_2$.
Thus, Statement-II is incorrect.
Answer: Statement I is correct but Statement II is incorrect
$2(+1) + 2x = 0 \Rightarrow x = -1$
In $\text{RbO}_2$, rubidium is an alkali metal with an oxidation state of $+1$. Let the oxidation state of oxygen be $y$.
$+1 + 2y = 0 \Rightarrow y = -\dfrac{1}{2}$
Thus, Statement-I is correct.
In $\text{HAuCl}_4$, the oxidation state of Au is $+3$. Its Stock notation is $\text{HAu(III)Cl}_4$.
In $\text{MnO}_2$, the oxidation state of Mn is $+4$. Its Stock notation is $\text{Mn(IV)O}_2$, not $\text{Mn(II)O}_2$.
Thus, Statement-II is incorrect.
Answer: Statement I is correct but Statement II is incorrect
Hence, the correct answer is option: 'C'.