Question

Match column \(I\) with column \(II\) for the oxidation states of the central atoms

\(\begin{array}{|c|c|c|c|}
\hline
\text{} & \text{Column I} & \text{} & \text{Column II}\\\hline
\text{A} & \text{\(Cr_2O_7^{2−}\)} & \text{(i)} & \text{+3}\\\hline
\text{B} & \text{\(MnO_4^−\)} & \text{(ii)} & \text{+4}\\\hline
\text{C} & \text{\(VO_3^−\)} & \text{(iii)} & \text{+5}\\\hline
\text{D} & \text{\(FeF_6^{3−}\)} & \text{(iv)} & \text{+6}\\\hline
\text{} & \text{} & \text{(e)} & \text{+7}\\\hline
\end{array}\)

Answer 1

\(\begin{array}{|c|c|c|c|}
\hline
\text{} & \text{Column I} & \text{} & \text{Column II}\\\hline
\text{A} & \text{\(Cr_2O_7^{2−}\)} & \text{(iv)} & \text{+7}\\\hline
\text{B} & \text{\(MnO_4^−\)} & \text{(v)} & \text{+8}\\\hline
\text{C} & \text{\(VO_3^−\)} & \text{(iii)} & \text{+6}\\\hline
\text{D} & \text{\(FeF_6^{3−}\)} & \text{(i)} & \text{+3}\\\hline
\end{array}\)

\(Cr_2O_7^{2−}\)
Let oxidation state of \(Cr\) be a
Oxidation state of \(O =−2\)
\(2\times a + 7\times (−2) =−2\)
\(2a−14=−2\)
\(2a=12\)
\(a=+6\)
Thus, oxidation state of \(Cr\) in \(Cr_2O_7^{2−}\) is \(+6\).

\(MnO_4^−\)
Let oxidation state of \(Mn\) be b and oxidation number of oxygen is \(-2\).So,
\(b+4\times (−2)=−1\)
\(b−8=−1\)
\(b=+7\)
Thus, oxidation state of \(Mn\) in \(MnO_4^−\) is \(+7\).

\(VO_3^−\)
Let oxidation state of \(V\) be c and oxidation number of oxygen is \(-2\). So,
\(c+3\times (−2)=−1\)
\(c−6=−1\)
\(c=+5\)
Thus, oxidation state of \(V\) in \(VO_3^−\) is \(+5\).

\(FeF_6^{3−}\)
Let oxidation state of \(Fe\) be \(d\) and oxidation number of fluorine is \(-1\). So,
\(d+6\times (−1)=−3\)
\(d−6=−3\)
\(d=+3\)
Thus, oxidation state of \(Fe\) in \(FeF_6^{3−}\) is \(+3\).

Hence, the correct answer is: \((A)\rightarrow (iv), (B)\rightarrow (v), (C)\rightarrow (iii), (D)\rightarrow (i)\)