1.1.3.2 Change of Oxidation Number MCQ

The following ionic equation represents the reaction between acidified potassium dichromate(VI) solution and iron(II) sulphate solution.
\[
\mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}+6 \mathrm{Fe}^{2+} \rightarrow 6 \mathrm{Fe}^{3+}+2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O}
\]
What is the change of oxidation number of chromium in the reaction?

The following equation represents the oxidation reaction between ethanol and acidified potassium dichromate(VI).
\[
\begin{aligned}
& 3 \mathrm{C}_2 \mathrm{H}_5 \mathrm{OH}+2 \mathrm{~K}_2 \mathrm{Cr}_2 \mathrm{O}_7+8 \mathrm{H}_2 \mathrm{SO}_4 \rightarrow \\
& \quad 3 \mathrm{CH}_3 \mathrm{COOH}+2 \mathrm{Cr}_2\left(\mathrm{SO}_4\right)_3+2 \mathrm{~K}_2 \mathrm{SO}_4+11 \mathrm{H}_2 \mathrm{O}
\end{aligned}
\]

What is the change in the oxidation number of the element chromium in this reaction?

Diagram 6 shows the chemical formula of a compound.

                       
the IUPAC name and oxidation number of copper element in the compound?

\begin{align}
\begin{array}{|c|l|c|}
\hline & \text { Name of compound } & \begin{array}{l}
\text { Oxidation number of } \\
\text { copper element }
\end{array} \\
\hline \text { A } & \text { Copper(I) oxide } & +1 \\
\hline \text { B } & \text { Copper(I) oxide } & +2 \\
\hline \text { C } & \text { Copper(II) oxide } & +1 \\
\hline \text { D } & \text { Copper(II) oxide } & +2 \\
\hline
\end{array}
\end{align}

The following chemical equation represents the extraction of silicon from quartz using coke.
\[
\mathrm{SiO}_2+\mathrm{C} \longrightarrow \mathrm{Si}+\mathrm{CO}_2
\]
What is the change in oxidation number of silicon?

The following ionic equation shows the reaction between zinc and acid.
\[
\mathrm{Zn}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \rightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})
\]
What is the change in oxidation number of hydrogen?

Which of the following IUPAC names are correct for the respective formulae of substances?

The equation below shows the decomposition of potassium chlorate.

2KClO₃ → 2KCl + 3O₂

Which of the following shows the change of oxidation number of chlorine in the reaction?