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D and F Block Elements question

2021 · 25 Jul · Shift 1 · Q12
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D and F Block Elements question

2021 · 25 Jul · Shift 1 · Q12

JEE MainChemistryD and F Block ElementsMCQ+4 / −1
The correct order of following 3d metal oxides, according to their oxidation numbers is : (a) CrO3CrO_3CrO3​, (b) Fe2O3Fe_2O_3Fe2​O3​, (c) MnO2MnO_2MnO2​, (d) V2O5V_2O_5V2​O5​, (e) Cu2OCu_2OCu2​O
  1. A
    (d) > (a) > (b) > (c) > (e)
  2. B
    (a) > (c) > (d) > (b) > (e)
  3. C
    (a) > (d) > (c) > (b) > (e)
  4. D
    (c) > (a) > (d) > (e) > (b)
View written solutionFree

Correct answer: C

  1. Find oxidation state of metal in each oxide

Use oxygen as −2-2−2.

  • (a) CrO3CrO_3CrO3​ x+3(−2)=0x + 3(-2)=0x+3(−2)=0 x−6=0⇒x=+6x-6=0 \Rightarrow x=+6x−6=0⇒x=+6

  • (b) Fe2O3Fe_2O_3Fe2​O3​ 2x+3(−2)=02x + 3(-2)=02x+3(−2)=0 2x−6=0⇒x=+32x-6=0 \Rightarrow x=+32x−6=0⇒x=+3

  • (c) MnO2MnO_2MnO2​ x+2(−2)=0x + 2(-2)=0x+2(−2)=0 x−4=0⇒x=+4x-4=0 \Rightarrow x=+4x−4=0⇒x=+4

  • (d) V2O5V_2O_5V2​O5​ 2x+5(−2)=02x + 5(-2)=02x+5(−2)=0 2x−10=0⇒x=+52x-10=0 \Rightarrow x=+52x−10=0⇒x=+5

  • (e) Cu2OCu_2OCu2​O 2x+(−2)=02x + (-2)=02x+(−2)=0 2x=2⇒x=+12x=2 \Rightarrow x=+12x=2⇒x=+1

  1. Arrange in decreasing order of oxidation number

We get:

  • CrO3:+6CrO_3 : +6CrO3​:+6
  • V2O5:+5V_2O_5 : +5V2​O5​:+5
  • MnO2:+4MnO_2 : +4MnO2​:+4
  • Fe2O3:+3Fe_2O_3 : +3Fe2​O3​:+3
  • Cu2O:+1Cu_2O : +1Cu2​O:+1

So the correct order is CrO3>V2O5>MnO2>Fe2O3>Cu2OCrO_3 > V_2O_5 > MnO_2 > Fe_2O_3 > Cu_2OCrO3​>V2​O5​>MnO2​>Fe2​O3​>Cu2​O

In symbols: (a)>(d)>(c)>(b)>(e)(a) > (d) > (c) > (b) > (e)(a)>(d)>(c)>(b)>(e)

  1. Match with options

This corresponds to Option C.

  1. Compare with stored correct answer

Stored correct answer is C, which matches our derived answer.

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