Redox Reactions Chapter-Wise Test 19

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following is a combination reaction that is also a redox reaction?

In \( \ce{C + O2 -> CO2} \), C (0) is oxidized to +4, and O₂ (0) is reduced to -2, making it a redox combination reaction.

\( \ce{C + O2 -> CO2} \)
\( \ce{CaO + CO2 -> CaCO3} \)
\( \ce{NH3 + HCl -> NH4Cl} \)
\( \ce{NaCl + AgNO3 -> AgCl + NaNO3} \)
1

Which compound contains an element with an oxidation number lower than in \( \ce{CO2} \)?

C in \( \ce{CO2} \): +4. In \( \ce{CH2O} \): \( x + 2(+1) + (-2) = 0 \), \( x = 0 \), which is lower.

\( \ce{CO} \)
\( \ce{CCl4} \)
\( \ce{CH2O} \)
\( \ce{HCOOH} \)
3

Which reaction demonstrates the removal of hydrogen, indicating an oxidation process?

Oxidation can involve hydrogen loss. In \( \ce{CH3OH + O -> HCHO + H2O} \), CH₃OH loses hydrogen to form HCHO, indicating oxidation.

\( \ce{CH3OH + O -> HCHO + H2O} \)
\( \ce{2Na + 2H2O -> 2NaOH + H2} \)
\( \ce{H2 + F2 -> 2HF} \)
\( \ce{Fe + H2SO4 -> FeSO4 + H2} \)
1

What is the oxidation number of carbon in \( \ce{CO2} \)?

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

+2
-4
+4
0
3

Which of the following is not a redox reaction?

In \( \ce{Mg(OH)2 + 2HCl -> MgCl2 + 2H2O} \), no element changes oxidation state (Mg: +2, H: +1, O: -2, Cl: -1).

\( \ce{2H2S + SO2 -> 3S + 2H2O} \)
\( \ce{Zn + H2SO4 -> ZnSO4 + H2} \)
\( \ce{2FeCl3 + H2 -> 2FeCl2 + 2HCl} \)
\( \ce{Mg(OH)2 + 2HCl -> MgCl2 + 2H2O} \)
4

In \( \ce{Hg2Cl2 + Cl2 -> 2HgCl2} \), what is the change in oxidation number of mercury?

Hg (+1 in \( \ce{Hg2Cl2} \)) becomes +2 in \( \ce{HgCl2} \). Change = +2 - (+1) = +1.

+2
+1
-1
0
2

In \( \ce{2CuSO4 + 4KI -> 2CuI + I2 + 2K2SO4} \), what is the total number of electrons transferred?

Cu (+2 to +1): 2 Cu atoms gain 2 electrons. I (-1 in 4\( \ce{KI} \)) to 0 in \( \ce{I2} \): 2 I atoms lose 2 electrons. Total = 2.

4
6
8
2
4

In \( \ce{3Sn + 4HNO3 -> 3SnO2 + 4NO + 2H2O} \), which species acts as the oxidizing agent?

\( \ce{HNO3} \) (N: +5) is reduced to \( \ce{NO} \) (N: +2), oxidizing Sn (0 to +4).

\( \ce{HNO3} \)
\( \ce{Sn} \)
\( \ce{SnO2} \)
\( \ce{NO} \)
1

In \( \ce{2H2S + 4F2 -> 2SF4 + 4HF} \), which element undergoes reduction?

F (0 in \( \ce{F2} \)) becomes -1 in \( \ce{SF4} \) and \( \ce{HF} \), gaining electrons; S (-2 to +4) is oxidized.

Sulfur
Fluorine
Hydrogen
None of these
2

In the reaction \( \ce{2F2 + 2H2O -> 4HF + O2} \), which element is oxidized?

O (-2 in \( \ce{H2O} \)) becomes 0 in \( \ce{O2} \), losing electrons.

Oxygen
Fluorine
Hydrogen
None of these
1

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