Redox Reactions Chapter-Wise Test 14

Correct answer Carries: 4.

Wrong Answer Carries: -1.

In the reaction \( \ce{3Br2 + 6NaOH -> 5NaBr + NaBrO3 + 3H2O} \), which species is the oxidizing agent?

\( \ce{Br2} \) (0) is reduced to -1 in \( \ce{NaBr} \) and oxidized to +5 in \( \ce{NaBrO3} \), acting as its own oxidizing agent.

\( \ce{NaOH} \)
\( \ce{Br2} \)
\( \ce{NaBr} \)
\( \ce{NaBrO3} \)
2

Identify the type of redox reaction: \( \ce{2H2O2 -> 2H2O + O2} \).

In \( \ce{2H2O2 -> 2H2O + O2} \), O (-1 in \( \ce{H2O2} \)) becomes -2 in \( \ce{H2O} \) and 0 in \( \ce{O2} \), indicating disproportionation.

Combination
Disproportionation
Displacement
Decomposition
2

Which reaction demonstrates the loss of electrons by a metal?

In \( \ce{2Al + 3Cl2 -> 2AlCl3} \), Al (0) loses electrons to become \( \ce{Al^3+} \) (+3).

\( \ce{2H2 + O2 -> 2H2O} \)
\( \ce{NaCl + AgNO3 -> AgCl + NaNO3} \)
\( \ce{2Al + 3Cl2 -> 2AlCl3} \)
\( \ce{CaCO3 -> CaO + CO2} \)
3

In \( \ce{2KBr + 3H2SO4 + 2MnO2 -> Br2 + 2MnSO4 + 2H2O + K2SO4} \), which element undergoes the largest increase in oxidation number?

Br (-1 in \( \ce{KBr} \)) to 0 in \( \ce{Br2} \): +1. Mn (+4 in \( \ce{MnO2} \)) to +2: -2. Br increases, Mn decreases; Br has the largest increase.

Manganese
Bromine
Sulfur
Oxygen
2

What is the oxidation number of carbon in \( \ce{CH3Cl} \)?

Let C = \( x \). H = +1, Cl = -1. Equation: \( x + 3(+1) + (-1) = 0 \), \( x + 3 - 1 = 0 \), \( x = -2 \).

+2
+1
0
-2
4

Which reaction shows oxidation by the removal of hydrogen without oxygen involvement?

In \( \ce{2HI + Cl2 -> 2HCl + I2} \), I (-1) loses H and electrons to become 0 in \( \ce{I2} \), with no oxygen present.

\( \ce{2HI + Cl2 -> 2HCl + I2} \)
\( \ce{CH4 + 2O2 -> CO2 + 2H2O} \)
\( \ce{2CuO + C -> 2Cu + CO2} \)
\( \ce{SO2 + H2O -> H2SO3} \)
1

In the reaction \( \ce{2K + 2NH3 -> 2KNH2 + H2} \), which process indicates oxidation of potassium?

Oxidation involves electron loss. K (0) becomes +1 in \( \ce{KNH2} \), losing electrons, while N (-3) and H rearrange without oxidizing.

Loss of electrons by K
Gain of oxygen by K
Loss of hydrogen by N
Gain of electrons by H
1

What is the oxidation number of osmium in \( \ce{OsO4} \)?

Let Os = \( x \). O = -2. Equation: \( x + 4(-2) = 0 \), \( x - 8 = 0 \), \( x = +8 \).

+6
+4
+8
+2
3

Which reaction involves the reduction of a non-metal?

In \( \ce{Br2 + H2S -> 2HBr + S} \), Br (0) is reduced to -1 in \( \ce{HBr} \).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Fe + 2HCl -> FeCl2 + H2} \)
\( \ce{Br2 + H2S -> 2HBr + S} \)
\( \ce{CaCO3 -> CaO + CO2} \)
3

What is the oxidation number of chlorine in \( \ce{HClO4} \)?

Let Cl = \( x \). H = +1, O = -2. Equation: \( +1 + x + 4(-2) = 0 \), \( 1 + x - 8 = 0 \), \( x = +7 \).

+5
+1
+7
-1
3

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