Redox Reactions Chapter-Wise Test 11

Correct answer Carries: 4.

Wrong Answer Carries: -1.

In the reaction \( \ce{2H2S + SO2 -> 3S + 2H2O} \), which species is oxidized?

Oxidation involves electron loss. S (-2 in \( \ce{H2S} \)) becomes 0 in \( \ce{S} \), losing electrons.

\( \ce{H2S} \)
\( \ce{SO2} \)
\( \ce{S} \)
\( \ce{H2O} \)
1

In the reaction \( \ce{2Fe + 3Cl2 -> 2FeCl3} \), what is the reducing agent?

The reducing agent is oxidized. Fe (0) loses electrons to become Fe (+3) in \( \ce{FeCl3} \), reducing Cl₂.

\( \ce{Cl2} \)
\( \ce{Fe} \)
\( \ce{FeCl3} \)
None of these
2

Which reaction involves a redox process where the oxidizing agent is a metal oxide?

In \( \ce{NiO + H2 -> Ni + H2O} \), \( \ce{NiO} \) (Ni: +2 to 0) is reduced, oxidizing \( \ce{H2} \) (0 to +1).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{S + O2 -> SO2} \)
\( \ce{NiO + H2 -> Ni + H2O} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
3

In the reaction \( \ce{2KMnO4 + 16H2SO4 + 10NaCl -> 5Cl2 + 2MnSO4 + 8H2O + 5Na2SO4 + K2SO4} \), how many electrons are transferred?

Oxidation: \( \ce{10Cl^- -> 5Cl2 + 10e^-} \). Reduction: \( \ce{2MnO4^- + 10e^- -> 2Mn^2+} \). Total electrons = 10.

5
8
12
10
4

What is the oxidation number of nitrogen in \( \ce{NO2} \)?

Let N = \( x \). O = -2. Equation: \( x + 2(-2) = 0 \), \( x - 4 = 0 \), \( x = +4 \).

+2
+3
+4
+5
3

Which of the following reactions involves the addition of oxygen to a substance, classifying it as an oxidation process?

Oxidation classically involves the addition of oxygen. In \( \ce{2Mg + O2 -> 2MgO} \), magnesium gains oxygen to form magnesium oxide, making it an oxidation reaction.

\( \ce{2Mg + O2 -> 2MgO} \)
\( \ce{2HgO -> 2Hg + O2} \)
\( \ce{H2 + Cl2 -> 2HCl} \)
\( \ce{CH4 + 2O2 -> CO2 + 2H2O} \)
1

In the reaction \( \ce{2H2O2 -> 2H2O + O2} \), what is the oxidizing agent?

\( \ce{H2O2} \) (O: -1) is reduced to -2 in \( \ce{H2O} \) and oxidized to 0 in \( \ce{O2} \); it acts as both, but here it oxidizes itself.

\( \ce{H2O} \)
\( \ce{O2} \)
\( \ce{H2O2} \)
None of these
3

In \( \ce{2Ga + 3Cl2 -> 2GaCl3} \), which species acts as the reducing agent?

Ga (0) becomes +3 in \( \ce{GaCl3} \), losing electrons to reduce Cl (0 to -1).

\( \ce{Ga} \)
\( \ce{Cl2} \)
\( \ce{GaCl3} \)
None of these
1

What is the change in oxidation number of sulfur in the reaction \( \ce{SO2 + H2O -> H2SO3} \)?

S (+4 in \( \ce{SO2} \)) remains +4 in \( \ce{H2SO3} \). Change = 0 (not a redox reaction).

+2
0
-2
+4
2

What is the oxidation number of hydrogen in \( \ce{NaH} \)?

In metal hydrides, H has an oxidation number of -1. For \( \ce{NaH} \): Na = +1, so \( +1 + x = 0 \), \( x = -1 \).

+2
-1
+1
0
2

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