Redox Reactions Chapter-Wise Test 5

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which reaction involves a redox process where the oxidizing agent is a compound with nitrogen?

In \( \ce{3Cu + 8HNO3 -> 3Cu(NO3)2 + 2NO + 4H2O} \), \( \ce{HNO3} \) (N: +5 to +2) is reduced, oxidizing Cu (0 to +2).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Fe + S -> FeS} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
\( \ce{3Cu + 8HNO3 -> 3Cu(NO3)2 + 2NO + 4H2O} \)
4

Which reaction is a combination redox reaction involving a non-metal?

In \( \ce{N2 + 3H2 -> 2NH3} \), N (0 to -3) is reduced, and H (0 to +1) is oxidized, forming one compound.

\( \ce{N2 + 3H2 -> 2NH3} \)
\( \ce{2Mg + CO2 -> 2MgO + C} \)
\( \ce{NaCl + KNO3 -> NaNO3 + KCl} \)
\( \ce{CaO + H2O -> Ca(OH)2} \)
1

What is the oxidation number of nitrogen in \( \ce{N2O} \)?

Let N = \( x \). O = -2. Equation: \( 2x + (-2) = 0 \), \( 2x = 2 \), \( x = +1 \).

+1
+2
-1
+3
1

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
+4
-2
0
3

Which reaction involves a redox process where the reducing agent contains a halogen?

In \( \ce{2NaI + MnO2 + 2H2SO4 -> I2 + MnSO4 + 2H2O + Na2SO4} \), \( \ce{NaI} \) (I: -1 to 0) is oxidized, reducing Mn (+4 to +2).

\( \ce{2Na + O2 -> Na2O2} \)
\( \ce{S + O2 -> SO2} \)
\( \ce{2NaI + MnO2 + 2H2SO4 -> I2 + MnSO4 + 2H2O + Na2SO4} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
3

Which of the following reactions involves the loss of hydrogen, indicating an oxidation process?

Oxidation can involve hydrogen loss. In \( \ce{CH3OH + O -> HCHO + H2O} \), C loses hydrogen, increasing its oxidation state from -2 to 0.

\( \ce{CH3OH + O -> HCHO + H2O} \)
\( \ce{2H2 + O2 -> 2H2O} \)
\( \ce{Fe + 2HCl -> FeCl2 + H2} \)
\( \ce{Na + H2O -> NaOH + H2} \)
1

Which element shows a fractional oxidation state in \( \ce{FeS2} \)?

In \( \ce{FeS2} \) (pyrite), Fe = +2, and S₂ acts as a peroxide-like unit with S = -1 (average). Sulfur’s state is fractional in context.

Iron
Oxygen
Hydrogen
Sulfur
4

In the reaction \( \ce{As2S3 + 7H2O2 + 2H2O -> 2H3AsO4 + 3H2SO4} \), which element’s oxidation number increases the most?

As (+3 in \( \ce{As2S3} \)) to +5 in \( \ce{H3AsO4} \): change = +2. S (-2 in \( \ce{As2S3} \)) to +6 in \( \ce{H2SO4} \): change = +8. S increases more.

Sulfur
Arsenic
Oxygen
Hydrogen
1

Which of the following is not a redox reaction?

In \( \ce{BaCl2 + H2SO4 -> BaSO4 + 2HCl} \), no element changes oxidation state; it’s a double displacement reaction.

\( \ce{2Na + 2H2O -> 2NaOH + H2} \)
\( \ce{Fe + CuSO4 -> FeSO4 + Cu} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
\( \ce{BaCl2 + H2SO4 -> BaSO4 + 2HCl} \)
4

Which of the following reactions involves both oxidation and reduction?

In \( \ce{4Fe + 3O2 -> 2Fe2O3} \), Fe (0 to +3) is oxidized, and O₂ (0 to -2) is reduced, making it a redox reaction.

\( \ce{4Fe + 3O2 -> 2Fe2O3} \)
\( \ce{NaOH + HCl -> NaCl + H2O} \)
\( \ce{CaCO3 -> CaO + CO2} \)
\( \ce{AgNO3 + NaCl -> AgCl + NaNO3} \)
1

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