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In chromite ore, the oxidation number of iron, and chromium are respectively
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Verified Answer
The correct answer is:
$+2,+3$
Chromite or chrome iron ore is $\mathrm{FeCr}_{2} \mathrm{O}_{4}$. Its actual composition is $\mathrm{FeO} \cdot \mathrm{Cr}_{2} \mathrm{O}_{3}$.
In $\mathrm{FeO}$, oxidation state of $\mathrm{Fe}$ is calculated as
$$
\begin{aligned}
\mathrm{x}+(-2) &=0 \\
\mathrm{x} &=+2
\end{aligned}
$$
Similarly, in $\mathrm{Cr}_{2} \mathrm{O}_{3}$, the oxidation state of $\mathrm{Cr}$ is calculated as
$$
\begin{aligned}
2 \times x+(-2) \times 3 &=0 \\
2 x &=+6 \\
x &=+3
\end{aligned}
$$
In $\mathrm{FeO}$, oxidation state of $\mathrm{Fe}$ is calculated as
$$
\begin{aligned}
\mathrm{x}+(-2) &=0 \\
\mathrm{x} &=+2
\end{aligned}
$$
Similarly, in $\mathrm{Cr}_{2} \mathrm{O}_{3}$, the oxidation state of $\mathrm{Cr}$ is calculated as
$$
\begin{aligned}
2 \times x+(-2) \times 3 &=0 \\
2 x &=+6 \\
x &=+3
\end{aligned}
$$
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