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Chapter 8: Redox Reactions

NCERT Solutions for CBSE Class 10 Chemistry — 29 solved questions with detailed explanations.

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Solved Questions

Q1. In the reaction 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺, the reducing agent is:

Fe³⁺
Fe²⁺
Sn²⁺
Sn⁴⁺

Difficulty: Easy-Medium · Topic: Redox

Solution

Sn²⁺ is oxidized to Sn⁴⁺ (loses electrons), so it is the reducing agent.

Q2. The oxidation state of Cr in K₂Cr₂O₇ is:

+3
+6
+7
+4

Difficulty: Easy-Medium · Topic: Oxidation State

Solution

2(+1) + 2x + 7(-2) = 0. 2 + 2x - 14 = 0. x = +6.

Q3. The oxidation state of Mn in KMnO₄ is:

Difficulty: Easy-Medium · Topic: Oxidation Number

Solution

K(+1) + Mn(x) + 4O(-2) = 0. 1 + x - 8 = 0. x = +7.

Q4. The oxidation state of S in H₂SO₄ is:

+2
-2
+6
+4

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: S in H₂SO₄ = +6.

Q5. The oxidation state of N in HNO₃ is:

+3
+4
-3
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: N in HNO₃ = +5.

Q6. The oxidation state of Cl in HClO₄ is:

+1
+7
+5
+3

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: Cl in HClO₄ = +7.

Q7. The oxidation state of N in NO₂ is:

+2
+5
+4
+3

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: N in NO₂ = +4.

Q8. The oxidation state of S in Na₂S₂O₃ is:

+3
+2
+6
+4

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: S in Na₂S₂O₃ = +2.

Q9. The oxidation state of Fe in Fe₂O₃ is:

+6
+3
+2
+4

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: Fe in Fe₂O₃ = +3.

Q10. The oxidation state of C in CH₄ is:

-2
-4
+4
0

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: C in CH₄ = -4.

Q11. The oxidation state of Mn in MnO₂ is:

+2
+6
+4
+7

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: Mn in MnO₂ = +4.

Q12. The oxidation state of P in H₃PO₄ is:

+3
+5
-3
+4

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: P in H₃PO₄ = +5.

Q13. The oxidation state of Cr in CrO₄²⁻ is:

+3
+4
+2
+6

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By applying oxidation state rules: Cr in CrO₄²⁻ = +6.

Q14. Oxidation state of Mn in KMnO₄:

+8
+6
+7
+9

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Mn in KMnO₄ has oxidation state +7.

Q15. Oxidation state of Cr in K₂Cr₂O₇:

+5
+6
+7
+8

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Cr in K₂Cr₂O₇ has oxidation state +6.

Q16. Oxidation state of S in H₂SO₄:

+5
+6
+8
+7

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: S in H₂SO₄ has oxidation state +6.

Q17. Oxidation state of N in HNO₃:

+4
+6
+5
+7

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: N in HNO₃ has oxidation state +5.

Q18. Oxidation state of Cl in HClO₄:

+8
+9
+6
+7

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Cl in HClO₄ has oxidation state +7.

Q19. Oxidation state of N in NO₂:

+3
+6
+4
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: N in NO₂ has oxidation state +4.

Q20. Oxidation state of S in SO₂:

+3
+4
+6
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: S in SO₂ has oxidation state +4.

Q21. Oxidation state of Fe in Fe₂O₃:

+5
+2
+3
+4

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Fe in Fe₂O₃ has oxidation state +3.

Q22. Oxidation state of C in CH₄:

-4
-2
-3
-5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: C in CH₄ has oxidation state -4.

Q23. Oxidation state of Mn in MnO₂:

+4
+3
+6
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Mn in MnO₂ has oxidation state +4.

Q24. Oxidation state of P in H₃PO₄:

+6
+4
+7
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: P in H₃PO₄ has oxidation state +5.

Q25. Oxidation state of N in N₂O:

+3
+2
+1
0

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: N in N₂O has oxidation state +1.

Q26. Oxidation state of S in Na₂SO₃:

+6
+5
+4
+3

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: S in Na₂SO₃ has oxidation state +4.

Q27. Oxidation state of Cl in NaClO₃:

+7
+4
+6
+5

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: Cl in NaClO₃ has oxidation state +5.

Q28. Oxidation state of N in NH₄⁺:

-2
-4
-3
-1

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: N in NH₄⁺ has oxidation state -3.

Q29. Oxidation state of S in SF₆:

+7
+5
+8
+6

Difficulty: Easy-Medium · Topic: Oxidation States

Solution

By rules: S in SF₆ has oxidation state +6.

Other Chapters in Chemistry

Ch 1: Some Basic Concepts Ch 2: Structure of Atom Ch 3: Classification of Elements Ch 4: Chemical Bonding Ch 5: States of Matter Ch 6: Thermodynamics Ch 7: Equilibrium Ch 9: Hydrogen Ch 10: s-Block Elements Ch 11: p-Block Elements Ch 12: Organic Chemistry Ch 13: Hydrocarbons Ch 14: Environmental Chemistry

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