1. Which of the following transition elements shows the highest oxidation state?

1. Which of the following transition elements shows the highest oxidation state? +

Correct Answer

Manganese (Mn) — maximum oxidation state = +7

Detailed Explanation

Among the first-row transition elements, Mn (Z = 25) shows the highest oxidation state. Its electronic configuration is:

Mn: [Ar] 3d⁵ 4s²

Mn can utilize all seven valence electrons from the 3d and 4s subshells, giving it a maximum oxidation state of:

+7

The +7 oxidation state is found in compounds such as KMnO₄. In permanganate:

x + 4(−2) = −1
x = +7

Therefore, manganese exhibits the highest oxidation state among the 3d-series transition elements.

Important Trend

For the first transition series, the maximum oxidation state generally increases from Sc to Mn and then decreases:

Sc(+3) → Ti(+4) → V(+5) → Cr(+6) → Mn(+7) → Fe → Co → Ni

Mn is exceptional because it has a half-filled 3d⁵ configuration and can involve all seven outer electrons in bonding/oxidation.

Highest oxidation state in 3d series = Mn(+7)

Competitive Exam Shortcut

Remember the sequence:

Sc +3 → Ti +4 → V +5 → Cr +6 → Mn +7

The maximum oxidation state reaches +7 at Mn. Examples:

• KMnO₄ → Mn = +7
• K₂MnO₄ → Mn = +6
• K₂Cr₂O₇ → Cr = +6
• V₂O₅ → V = +5

30 Related MCQs with Solutions

1. Which transition element shows the highest oxidation state in the first transition series?

A. Cr

B. Mn

C. Fe

D. Co

Answer: B. Mn
Mn can attain +7 oxidation state.

2. The maximum oxidation state of Mn is:

A. +3

B. +5

C. +6

D. +7

Answer: D. +7

3. The oxidation state of Mn in KMnO₄ is:

A. +4

B. +5

C. +6

D. +7

Answer: D. +7

4. Which element has the configuration [Ar] 3d⁵4s²?

A. Cr

B. Mn

C. Fe

D. V

Answer: B. Mn

5. The highest oxidation state in the 3d series occurs at:

A. Sc

B. Cr

C. Mn

D. Fe

Answer: C. Mn

6. Which oxidation state is characteristic of permanganate ion?

A. +3

B. +5

C. +6

D. +7

Answer: D. +7

7. In MnO₄⁻, oxidation state of Mn is:

A. +5

B. +6

C. +7

D. +8

Answer: C. +7

8. Which sequence correctly represents increasing maximum oxidation states?

A. Sc < Ti < V < Cr < Mn

B. Mn < Cr < V < Ti

C. Fe < Mn < Cr < V

D. Ti < Sc < V < Mn

Answer: A

9. Maximum oxidation state of Cr is:

A. +3

B. +4

C. +6

D. +7

Answer: C. +6

10. Maximum oxidation state of V is:

A. +3

B. +4

C. +5

D. +6

Answer: C. +5

11. Maximum oxidation state of Ti is:

A. +2

B. +3

C. +4

D. +5

Answer: C. +4

12. Which element reaches oxidation state +6 in its common compounds?

A. Sc

B. Ti

C. Cr

D. Mn

Answer: C. Cr

13. Oxidation state of Mn in K₂MnO₄ is:

A. +4

B. +5

C. +6

D. +7

Answer: C. +6

14. Which ion contains Mn in its highest oxidation state?

A. Mn²⁺

B. MnO₄²⁻

C. MnO₄⁻

D. MnO₂

Answer: C. MnO₄⁻

15. The highest oxidation state of Mn is possible because:

A. It has seven valence electrons

B. It has no d-electrons

C. It is a noble gas

D. It has only 4s electrons

Answer: A
Mn has seven electrons in 3d and 4s orbitals available for bonding/oxidation.

16. Which transition metal is associated with the +7 oxidation state?

A. Mn

B. Ni

C. Cu

D. Zn

Answer: A. Mn

17. In which compound is Cr in +6 oxidation state?

A. CrCl₃

B. CrO

C. K₂Cr₂O₇

D. Cr₂O₃

Answer: C. K₂Cr₂O₇

18. Which element shows a maximum oxidation state equal to its group number?

A. Mn

B. Fe

C. Co

D. Ni

Answer: A. Mn

19. Which of the following is a strong oxidizing species containing Mn(+7)?

A. MnO₄⁻

B. Mn²⁺

C. MnO

D. MnCl₂

Answer: A

20. Which transition element has the greatest number of possible oxidation states in the first series?

A. Sc

B. Mn

C. Zn

D. Cu

Answer: B. Mn

21. The maximum oxidation state of Fe is commonly:

A. +2

B. +3

C. +6

D. +7

Answer: C. +6
High oxidation states such as +6 occur in ferrate(VI), FeO₄²⁻.

22. Which oxidation state is shown by manganese in MnO₂?

A. +2

B. +3

C. +4

D. +7

Answer: C. +4

23. Which compound contains Mn in the highest oxidation state?

A. MnCl₂

B. MnO₂

C. K₂MnO₄

D. KMnO₄

Answer: D. KMnO₄

24. Which oxidation state corresponds to manganate ion, MnO₄²⁻?

A. +4

B. +5

C. +6

D. +7

Answer: C. +6

25. The maximum oxidation state in the 3d series first rises up to:

A. V

B. Cr

C. Mn

D. Fe

Answer: C. Mn

26. Which element has half-filled 3d subshell and can show +7 oxidation state?

A. Cr

B. Mn

C. Fe

D. Co

Answer: B. Mn

27. In MnO₄⁻, total oxidation number contributed by oxygen atoms is:

A. −4

B. −6

C. −8

D. −10

Answer: C. −8
Four oxygen atoms contribute 4 × −2 = −8.

28. Which statement about maximum oxidation states of 3d elements is correct?

A. They continuously increase from Sc to Zn

B. They reach a maximum at Mn and then generally decrease

C. Zn shows +7

D. Sc shows +7

Answer: B

29. Which element is responsible for the +7 state in permanganate?

A. Chromium

B. Vanadium

C. Manganese

D. Iron

Answer: C. Manganese

30. The correct maximum oxidation-state sequence from Sc to Mn is:

A. +1, +2, +3, +4, +5

B. +3, +4, +5, +6, +7

C. +2, +3, +4, +5, +6

D. +3, +3, +4, +5, +6

Answer: B. +3, +4, +5, +6, +7

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