d and f-Block Elements Test

Result

d and f-Block Elements Test - 17

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Question 1/14
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Only One Option Correct Type
Direction (Q. Nos. 1-10) This section contains 10 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct.
Q.
Which is most basic oxide of chromium?

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A
CrO

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B
CrO₂

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C
CrC₃

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D
Cr₂O₃

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Solutions

Oxide having lower oxidation number is basic and as oxidation number increase, acidic nature increases.
Question 2/14
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The basic character of the transition metal monoxides follows the order
(Atomic Number, Ti = 22, V = 23, Cr = 24, Fe = 26)

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A
TiO > VO > CrO > FeO

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B
VO > CrO > TiO > FeO

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C
CrO > VO > FeO > TiO

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D
TiO > FeO > VO > CrO

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Solutions

TiO > VO > CrO > FeO with the decrease in size of metal atom from Ti to Fe, the basic character of their monoxides decreases.
Question 3/14
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MnO₄^- + S^2- + H⁺ → Mn²⁺ +S + H₂O When this equation is balanced, the total number of coefficients on the left hand side are

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A
15

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B
23

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C
17

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D
14

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Solutions
Question 4/14
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when this equation is balanced, the num ber of OF^- ions added

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A
4 OH^-ions on the left side

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B
2 OH^-ions on the left side

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C
4 OH^-ions on the right side

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D
2 OH^-ions on the right side

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Solutions
Question 5/14
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One mole of each KMnO₄ and K₂Cr₂O₇ can oxidise ........... moles of ferrous ion.

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A
5 and 5

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B
5 and 6

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C
6 and 5

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D
6 and 6

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Solutions

One equivalent of KMnO₄ = One equivalent of K₂Cr₂O₇ = One equivalent of Fe²⁺ ion or 1/5 moles of KMnO₄ = 1/6 moles of K₂Cr₂O₇ = One mole of Fe²⁺ ion.
Hence, one mole of KMnO₄ reacts with 5 moles of Fe²⁺ ion and one mole of K₂Cr₂O₇ reacts with 6 moles of Fe²⁺ ion.
Question 6/14
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is of intense pink colour, though Mn is in (+7) oxidation state. It is due to

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A
oxygen gives colour to it

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B
charge transfer when Mn gives its electron to oxygen

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C
character transfer when oxygen gives its electron to Mn making it Mn (+ VI) hence, coloured

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D
None of the above is correct

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Solutions

This is called ligand to metal charge transfer phenomenon.
Question 7/14
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Which of the following is incorrect statement?

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A
Both MnO₄^-, MnO₄^2- have tetrahedral shape

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B
MnO₄^- is purple while MnO₄^2- ion is green

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C
Both MnO₄^- and MnO₄^2- are diamagnetic

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D
MnO₄^- is diamagnetic while MnO₄^2- ion is paramagnetic

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Solutions

The green manganate is paramagnetic with one unpaired electron but the permanganate is diamagnetic.
Question 8/14
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Pyrolusite in MnO₂ is used to prepare KMnO₄. Steps are
Here, I and II are

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A
fused with KOH/air, electrolytic oxidation

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B
fused with KOH/air, electrolytic reduction

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C
fuse with cone. HNO₃/air, electrolytic oxidation

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D
All are correct

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Solutions
Question 9/14
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Which is the correct statem ent about structure?

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A
It has neither Cr—Cr bonds nor O—0 bonds

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B
It has one Cr—Cr bond and six O—O bond

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C
It has no Cr—Cr bonds and has six O—O bond

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D
It has one Cr—Cr bond and seven Cr—O bonds

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Solutions

The correct answer is Option A.
In a dichromate dianion structure, the negative charge can be on any O attached to Cr, therefore all Cr - O are equivalent. Also have Cr - O - Cr bond.
Question 10/14
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Out of Cr (VI) as , which is better oxidising agent?

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A
, basic medium

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B
, basic medium

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C
, acidic medium

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D
CrO₃, basic medium

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Solutions

+ 4H₂O + 3e^- → Cr(OH)₃ + 5OH^-, E° = - 0.13 V
+ 14H⁺ + 6e^- → 2Cr³⁺ + 7H₂O , E° = 1.33 V
Question 11/14
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Matching List Type
Direction (Q. Nos. 11 and 12) Choices for the correct combination of elements from Column I and Column II are given as options (a), (b), (c) and (d), out of which one is correct.
Q.
Match the Column I with Column II and mark the correct option from the codes given below.

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A

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B

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C

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D

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Solutions

(i) → (q,t) (ii) → (p.r) (iii) → (q.r.t) (iv) → (q,s)
Question 12/14
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Match the Column I with Column II and mark the correct option from the codes given below.

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A

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B

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C

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D

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Solutions

(i) → (q) (ii) → (s) (iii) → (r) (iv) → (p)
(i) In acidic medium,

Hence, = M/5
(ii) In strongly alkaline medium

Hence, = M/1
(iii) In neutral or weakly basic medium

Hence, = M/3

Hence, equivalent weight is M/6.
Question 13/14
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Statement Type
Direction (Q. Nos. 13 and 14) This section is based on Statement I and Statement II. Select the correct answer from the codes given below.
Q.
Statement I ; When a solution of potassium chromate is treated with an excess of dilute nitric acid chromate undergoes oxidation.
Statement II : Dichromate ions are produced in above process.

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A
Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

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B
Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I

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C
Statement I is correct but Statement II is incorrect

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D
Statement II is correct but Statement I is incorrect

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Solutions
Question 14/14
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Statement I : The oxidation state of chromium in the final product formed by the reaction between Kl and acidified potassium dichromate solution has green colour.
Statement II : The product has Cr³⁺ ions.

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A
Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

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B
Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I

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C
Statement I is correct but Statement II is incorrect

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D
Statement II is correct but Statement I is incorrect

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Solutions

Question 1/14

CrO

CrO2

CrC3

Cr2O3

Question 2/14

TiO > VO > CrO > FeO

VO > CrO > TiO > FeO

CrO > VO > FeO > TiO

TiO > FeO > VO > CrO

Question 3/14

15

23

17

14

Question 4/14

4 OH- ions on the left side

2 OH- ions on the left side

4 OH- ions on the right side

2 OH- ions on the right side

Question 5/14

5 and 5

5 and 6

6 and 5

6 and 6

Question 6/14

oxygen gives colour to it

charge transfer when Mn gives its electron to oxygen

character transfer when oxygen gives its electron to Mn making it Mn (+ VI) hence, coloured

None of the above is correct

Question 7/14

Both MnO4-, MnO42- have tetrahedral shape

MnO4- is purple while MnO42- ion is green

Both MnO4- and MnO42- are diamagnetic

MnO4- is diamagnetic while MnO42- ion is paramagnetic

Question 8/14

fused with KOH/air, electrolytic oxidation

fused with KOH/air, electrolytic reduction

fuse with cone. HNO3/air, electrolytic oxidation

All are correct

Question 9/14

It has neither Cr—Cr bonds nor O—0 bonds

It has one Cr—Cr bond and six O—O bond

It has no Cr—Cr bonds and has six O—O bond

It has one Cr—Cr bond and seven Cr—O bonds

Question 10/14

, basic medium

, basic medium

, acidic medium

CrO3, basic medium

Question 11/14

Question 12/14

Question 13/14

Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I

Statement I is correct but Statement II is incorrect

Statement II is correct but Statement I is incorrect

Question 14/14

Both Statement I and Statement II are correct and Statement II is the correct explanation of Statement I

Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I

Statement I is correct but Statement II is incorrect

Statement II is correct but Statement I is incorrect

CrO₂

CrC₃

Cr₂O₃

4 OH^-ions on the left side

2 OH^-ions on the left side

4 OH^-ions on the right side

2 OH^-ions on the right side

Both MnO₄^-, MnO₄^2- have tetrahedral shape

MnO₄^- is purple while MnO₄^2- ion is green

Both MnO₄^- and MnO₄^2- are diamagnetic

MnO₄^- is diamagnetic while MnO₄^2- ion is paramagnetic

fuse with cone. HNO₃/air, electrolytic oxidation

CrO₃, basic medium