Redox Reactions Chapter-Wise Test 9

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which reaction involves a redox process where the reducing agent loses electrons without gaining oxygen?

In \( \ce{2Co + Br2 -> 2CoBr} \), Co (0 to +1) loses electrons to reduce Br (0 to -1), with no oxygen involved.

\( \ce{2Co + Br2 -> 2CoBr} \)
\( \ce{2Mg + O2 -> 2MgO} \)
\( \ce{C + O2 -> CO2} \)
\( \ce{2CuO + CO -> 2Cu + CO2} \)
1

Which reaction involves a redox process where the oxidizing agent gains electrons without oxygen loss?

In \( \ce{2Na + Br2 -> 2NaBr} \), \( \ce{Br2} \) (Br: 0 to -1) gains electrons, oxidizing Na (0 to +1), no oxygen involved.

\( \ce{2Na + Br2 -> 2NaBr} \)
\( \ce{Fe2O3 + 3CO -> 2Fe + 3CO2} \)
\( \ce{MnO2 + 4HCl -> MnCl2 + Cl2 + 2H2O} \)
\( \ce{PbO + C -> Pb + CO} \)
1

Which compound contains carbon with an oxidation number higher than in \( \ce{CH4} \)?

C in \( \ce{CH4} \): -4. In \( \ce{CHCl3} \): \( x + 1 + 3(-1) = 0 \), \( x - 2 = 0 \), \( x = +2 \), which is higher.

\( \ce{C2H6} \)
\( \ce{CH3OH} \)
\( \ce{CHCl3} \)
\( \ce{C2H2} \)
3

How many electrons are transferred in the balanced reaction \( \ce{2MnO4^- + 6I^- + 4H2O -> 2MnO2 + 3I2 + 8OH^-} \)?

Oxidation: \( \ce{6I^- -> 3I2 + 6e^-} \). Reduction: \( \ce{2MnO4^- + 6e^- -> 2MnO2} \). Total electrons = 6.

2
4
8
6
4

In \( \ce{2HNO3 + 3H3AsO3 -> 2NO + 3H3AsO4 + H2O} \), how many electrons are transferred per mole of \( \ce{HNO3} \)?

N (+5 in \( \ce{HNO3} \)) to +2 in \( \ce{NO} \): 2 N gain 6 electrons. As (+3 to +5): 3 As lose 6 electrons. Per \( \ce{HNO3} \) = 6/2 = 3.

2
4
3
6
3

Which reaction involves a disproportionation process with a halogen?

In \( \ce{3F2 + 3H2O -> 6HF + O3} \), F (0) is reduced to -1 in \( \ce{HF} \) and O (-2 to 0 in \( \ce{O3} \)) is oxidized, but F drives it indirectly.

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{3F2 + 3H2O -> 6HF + O3} \)
\( \ce{Fe + Br2 -> FeBr2} \)
\( \ce{2KI + Cl2 -> 2KCl + I2} \)
2

Which of the following is a disproportionation reaction?

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

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Fe + CuSO4 -> FeSO4 + Cu} \)
\( \ce{3HNO2 -> HNO3 + 2NO + H2O} \)
\( \ce{2KClO3 -> 2KCl + 3O2} \)
3

In the reaction \( \ce{2I2 + 2H2O -> 4HI + O2} \), which element is reduced?

Reduction involves electron gain. I (0 in \( \ce{I2} \)) becomes -1 in \( \ce{HI} \), gaining electrons.

Iodine
Oxygen
Hydrogen
None of these
1

In \( \ce{2VCl3 + Cl2 -> 2VCl4} \), how many electrons are lost per vanadium atom?

V (+3 in \( \ce{VCl3} \)) to +4 in \( \ce{VCl4} \): change = +4 - (+3) = +1; each V loses 1 electron.

1
2
3
4
1

In \( \ce{2Ag2O + C -> 4Ag + CO2} \), which element’s oxidation number changes by the largest magnitude?

Ag (+1 to 0): change = -1. C (0 to +4 in \( \ce{CO2} \)): change = +4. C has the largest magnitude change.

Silver
Oxygen
Carbon
None of these
3

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