MCQ of d-block elements

1. KMnO4 is coloured due to:

(a) d-d transitions

(b) charge transfer from ligand to metal

(d) charge transfer from metal to ligand

Ans. (b) charge transfer from ligand to metal

2. In which of the following pairs of ions, the lower oxidation state in aqueous solution is more stable than the other?

(a) Ti+, Ti3+ (b) Cu+, Cu2+

Ans. (A) (a) Ti+, Ti3+

3. Which of the following is likely to form white salts?

(a) Cu2+ (b) Sc3+

(b) Sc3+

4. When KMnO4 solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because:

(a) CO2 is formed as the product.

(b) Reaction is exothermic.

(d) Mn2+ acts as autocatalyst.

Ans. (d) Mn2+ acts as autocatalyst.

5. In which of the following does the central atom exhibit an oxidation state of +4?
(a) K₂[Ni(CN)₄]

(b) [Cu(NH₃)₄]²⁺

(d) [Pt(en)₂Cl₂]²⁺

Ans D

6. Metallic radii of some transition elements are given below. Which of these elements will have highest density?

Element	Fe	Co	Ni	Cu
Metallic radii/pm	126	125	125	128

(a) Fe (b) Ni (c) Co (d) Cu

Ans D

7. Which of the following statements is not correct?

(a) Copper liberates hydrogen from acids.

(b) In its higher oxidation states, manganese forms stable compounds with oxygen and fluorine.

(d) Ti2+ and Cr2+ are reducing agents in aqueous solution.

Ans A

8. Which of the following is amphoteric oxide?
Mn₂0₇, CrO₃, Cr₂O₃, CrO V₂O₅, V₂O₄

(a) V₂O₅, Cr₂O₃

(b) Mn₂O₇, CrO₃

(d) V₂O₅, V₂O₄

Ans a

9. Which one of the following does not correctly represent the correct order of the property indicated against it ?

(a) Ti < V < Cr < Mn, increasing number of oxidation states

(b) Ti < V < Mn < Cr, increasing second ionisation enthalpy

(d) Ti³⁺ < V³⁺ < Cr³⁺ < Mn³⁺ , increasing magnetic moment
Ans C

10. Which set of ions exhibit specific colours?

(Atomic number of Sc = 21, Ti = 22, V=23, Mn = 25, = 26, Ni = 28, cu = 29 and Zn =30)

(a) sc³⁺, Ti⁴⁺, Mn³⁺

(b) Sc³⁺, Zn²⁺, Ni²⁺
(c) V³⁺, V²⁺, Fe³⁺

(d) Ti³⁺ , Ti⁴⁺ , Ni²⁺
Ans C

11. The magnetic moment is associated with its spin angular momentum and orbital angular momentum. Spin only magnetic moment value of Cr3+ ion is

(a) 2.87 B.M.

(b) 3.87 B.M.

(d) 3.57 B.M.
Ans B

12. Transition elements show magnetic moment due to spin and orbital motion of electrons. Which of the following metallic ions have almost same spin only magnetic moment?

(a) Co²⁺

(b) Cr²⁺
(c) Mn²⁺

(d) Cr³⁺
Ans A

13. The electronic configuration of Cu(II) is 3d⁹ whereas that of Cu(I) is 3d¹⁰. Which of the following is correct?

(a) Cu(II) is more stable

(b) Cu(II) is less stable

(d) Stability of Cu(I) and Cu(II) depends on nature of copper salts

Ans A

14. Generally transition elements form coloured salts due to the presence of unpaired electrons. Which of the following compounds will be coloured in solid state?

(a) Ag₂SO₄

(b) CuF₂

(d) Cu₂Cl₂
Ans b

15. Which of the following is the reason for Zinc not exhibiting variable oxidation state?

(a) Inert pair effect

(b) Completely filled 3d subshell

(d) Common ion effect

Ans b

16. Which of the following is a diamagnetic ion? (Atomic numbers of sc, V, Mn and Cu are 21, 23, 25 and 29 respectively)

(a) V²⁺
(b) Sc³⁺

(d) Mn³⁺
Ans b

17. Out of the following transition elements, the maximum number of oxidation states are shown by

(a) Sc (Z = 21)

(b) Cr (Z = 24)

(d) Fe (Z = 26)
Ans C

18. The incorrect statement about interstitial compounds is

(a) They are chemically reactive.

(b) They are very hard.

(d) They have high melting point.

Ans A

19. The most common and stable oxidation state of a Lanthanoid is:

(a)+2 (b) +3 (c) +4 (d) +6

Ans b

20. Which of the following characteristics of transition metals is associated with their catalytic activity?

(a) Paramagnetic nature

(b) Colour of hydrated ions

(d) Variable oxidation states

Ans d

21. The magnetic moment of [NiCl₄]^2-

[Atomic number: Ni = 28]

(a) 1.82 BM

(b) 2.82 BM

(d) 5.46 BM
Ans b

22. Which property of transition metals enables them to behave as catalysts?

(a) High melting point

(b) High ionisation enthalpy

(d) Variable oxidation states

Ans d

23. When acidified K₂Cr₂O₇ solution is added to Sn salts then Sn²⁺ changes to

(a) Sn (b) Sn³⁺

Ans. Correct option : (c)

24. KMnO₄ acts as an oxidizing agent in acidic medium. The number of moles of KMnO4 that will be needed to react with one mole of sulphide ions in acidic solution is

(a) 2/5 (b) 3/5

Ans. Correct option : (a)

25. There are 14 elements in actinoid series. Which of the following element does not belong to this series?

(a) U (b) Np

Ans. Correct option : (c)

26. Electronic configuration of a transition element X in +3 oxidation state is [Ar]3d⁵. What is its atomic number?

(a) 25

(b) 26

(d) 24

Ans (b) Electronic configuration of is [Ar]3d5

27. On addition of small amount of KMnO₄ to concentrated H₂SO₄, a green oily compound is obtained which is highly explosive in nature. Identify the compound from the following.

(a) Mn₂O₇

(b) MnO₂

(d) Mn₂O₃

Ans A

28. When KMnO₄ solution is added to oxalic acid solution, the decolourisation is slow in the beginning but becomes instantaneous after some time because

(a) CO₂ is formed as the product

(b) reaction is exothermic

(d) Mn²⁺ acts as autocatalyst

Ans D

29. Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of metals. Which of the following is not the characteristic property of interstitial compounds?

(a) They have high melting points in comparison to pure metals

(b) They are very hard

(d) The are chemically very reactive

Ans D

30. KMnO₄ acts as an oxidising agent in alkaline medium. When alkaline

KMnO₄ is treated with KI, iodide ion is oxidised to …………..

(a) I₂

(b) IO^–

(d) IO₄^–

Ans C

MCQ of d-block elements

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