Redox Reactions Chapter-Wise Test 1

Correct answer Carries: 4.

Wrong Answer Carries: -1.

What is the change in oxidation number of sulfur in the reaction \( \ce{S + 2H2SO4 -> 3SO2 + 2H2O} \)?

S (0) becomes +4 in \( \ce{SO2} \). Change = +4 - 0 = +4.

+2
+4
+6
-4
2

In the reaction \( \ce{2Cu2O + Cu2S -> 6Cu + SO2} \), which element is reduced?

Cu (+1 in \( \ce{Cu2O} \) and \( \ce{Cu2S} \)) decreases to 0 in \( \ce{Cu} \), indicating reduction.

Sulfur
Oxygen
Copper
None of these
3

Which reaction involves a redox process where the reducing agent is a metal hydride?

In \( \ce{2NaH + O2 -> Na2O2 + H2} \), \( \ce{NaH} \) (H: -1 to 0 in \( \ce{H2} \)) is oxidized, reducing \( \ce{O2} \) (0 to -1).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{Fe + S -> FeS} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
\( \ce{2NaH + O2 -> Na2O2 + H2} \)
4

What is the oxidation number of carbon in \( \ce{C2H2} \)?

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

+2
+1
-2
-1
4

Which of the following is a redox reaction involving a metal?

In \( \ce{4Li + O2 -> 2Li2O} \), Li (0) is oxidized to +1, and O (0) is reduced to -2.

\( \ce{NaCl + AgNO3 -> AgCl + NaNO3} \)
\( \ce{Ca(OH)2 + CO2 -> CaCO3 + H2O} \)
\( \ce{NH3 + HCl -> NH4Cl} \)
\( \ce{4Li + O2 -> 2Li2O} \)
4

Which of the following reactions does not involve a change in oxidation state?

In \( \ce{KOH + HNO3 -> KNO3 + H2O} \), all elements retain their oxidation states (K: +1, O: -2, H: +1, N: +5).

\( \ce{2H2 + O2 -> 2H2O} \)
\( \ce{Cu + 2AgNO3 -> Cu(NO3)2 + 2Ag} \)
\( \ce{KOH + HNO3 -> KNO3 + H2O} \)
\( \ce{2FeCl2 + Cl2 -> 2FeCl3} \)
3

Which reaction represents a displacement redox reaction?

In \( \ce{Zn + CuSO4 -> ZnSO4 + Cu} \), Zn displaces Cu, with Zn oxidizing (0 to +2) and Cu reducing (+2 to 0).

\( \ce{2Na + Cl2 -> 2NaCl} \)
\( \ce{2H2O -> 2H2 + O2} \)
\( \ce{Zn + CuSO4 -> ZnSO4 + Cu} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
3

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

In \( \ce{2Fe + 3I2 -> 2FeI3} \), \( \ce{I2} \) (I: 0 to -1) is reduced, oxidizing Fe (0 to +3).

\( \ce{2Na + O2 -> Na2O2} \)
\( \ce{S + O2 -> SO2} \)
\( \ce{2H2O2 -> 2H2O + O2} \)
\( \ce{2Fe + 3I2 -> 2FeI3} \)
4

What is the oxidation number of vanadium in \( \ce{VOSO4} \)?

Let V = \( x \). O = -2, \( \ce{SO4^2-} \) = -2. In \( \ce{VO} \): \( x + (-2) = +2 \) (cation charge), \( x = +4 \). Total: \( +4 + (-2) = 0 \).

+2
+3
+4
+5
3

What is the change in oxidation number of nitrogen in the reaction \( \ce{N2 -> 2NH3} \)?

N (0 in \( \ce{N2} \)) becomes -3 in \( \ce{NH3} \). Change = -3 - 0 = -3.

+3
-3
+6
-6
2

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