Redox Reactions Chapter-Wise Test 10

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which reaction involves a redox process where oxygen is neither gained nor lost by the element oxidized?

In \( \ce{2FeSO4 + I2 -> Fe2(SO4)3 + 2HI} \), Fe (+2 to +3) is oxidized without oxygen change; I (+2 to -1) is reduced.

\( \ce{2Na + O2 -> Na2O2} \)
\( \ce{S + O2 -> SO2} \)
\( \ce{2FeSO4 + I2 -> Fe2(SO4)3 + 2HI} \)
\( \ce{2CuO + C -> 2Cu + CO2} \)
3

Which reaction involves a redox process where a single element acts as both oxidizing and reducing agent?

In \( \ce{3HNO2 -> HNO3 + 2NO + H2O} \), N (+3) in \( \ce{HNO2} \) is oxidized to +5 in \( \ce{HNO3} \) and reduced to +2 in \( \ce{NO} \), a disproportionation.

\( \ce{3HNO2 -> HNO3 + 2NO + H2O} \)
\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Fe + CuSO4 -> FeSO4 + Cu} \)
\( \ce{2H2 + O2 -> 2H2O} \)
1

What is the oxidation number of oxygen in \( \ce{O3} \)?

In its elemental form, \( \ce{O3} \) (ozone), oxygen has an oxidation number of 0.

-2
-1
+2
0
4

Which reaction involves a redox process where the oxidizing agent contains sulfur?

In \( \ce{2Fe + 3SO2 -> Fe2O3 + 3S} \), \( \ce{SO2} \) (S: +4 to 0) is reduced, oxidizing Fe (0 to +3).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{C + O2 -> CO2} \)
\( \ce{2Fe + 3SO2 -> Fe2O3 + 3S} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
3

In the reaction \( \ce{2MnO2 + 2KOH + O2 -> 2K2MnO4 + H2} \), which element is reduced?

H (+1 in \( \ce{KOH} \)) becomes 0 in \( \ce{H2} \), gaining electrons.

Manganese
Hydrogen
Oxygen
Potassium
2

Which of the following reactions is an example of disproportionation?

In \( \ce{Cl2 + 2NaOH -> NaCl + NaClO + H2O} \), Cl (0) is both oxidized to +1 (\( \ce{NaClO} \)) and reduced to -1 (\( \ce{NaCl} \)).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Zn + CuSO4 -> ZnSO4 + Cu} \)
\( \ce{Cl2 + 2NaOH -> NaCl + NaClO + H2O} \)
\( \ce{2KClO3 -> 2KCl + 3O2} \)
3

Which element undergoes reduction in the reaction \( \ce{2Na + 2H2O -> 2NaOH + H2} \)?

H (+1 in \( \ce{H2O} \)) reduces to 0 in \( \ce{H2} \), gaining electrons.

Sodium
Oxygen
Nitrogen
Hydrogen
4

Which reaction represents a decomposition redox process?

In \( \ce{2KClO3 -> 2KCl + 3O2} \), Cl (+5 to -1) is reduced, and O (-2 to 0) is oxidized.

\( \ce{CaCO3 -> CaO + CO2} \)
\( \ce{2KClO3 -> 2KCl + 3O2} \)
\( \ce{NH4Cl -> NH3 + HCl} \)
\( \ce{2NaHCO3 -> Na2CO3 + H2O + CO2} \)
2

What is the oxidation number of sulfur in \( \ce{S4O6^2-} \)?

Let S = \( x \). O = -2. Equation: \( 4x + 6(-2) = -2 \), \( 4x - 12 = -2 \), \( 4x = 10 \), \( x = +2.5 \) (average).

+2
+4
+6
+2.5
4

In \( \ce{2FeCl3 + H2S -> 2FeCl2 + S + 2HCl} \), which species contains the element reduced?

Fe (+3 in \( \ce{FeCl3} \)) to +2 in \( \ce{FeCl2} \) is reduced; S (-2 to 0) is oxidized.

\( \ce{H2S} \)
\( \ce{S} \)
\( \ce{FeCl3} \)
\( \ce{HCl} \)
3

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