d and f-Block Elements Test

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d and f-Block Elements Test - 5

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Question 1/4
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Directions For Questions

The following question has four choices, out of which ONLY ONE is correct.

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Which of the following combinations in an aqueous medium will give a red colour or precipitate?

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A
Fe³⁺ + SCN^-

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B
Fe²⁺ + [Fe(CN)₆]^3-

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C
Ni²⁺ + NH₃

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D
Cu²⁺ + SCN^-

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Solutions

Fe⁺³+ 3SCN^- → Fe(SCN)₃
Ferric thiocyanate forms a a blood red colouration.
Question 2/4
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Which of the following rules should be obeyed while preparing the alloys?

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A
The difference in the atomic radii should be less than 15%.

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B
Valence electronic configuration should be the same.

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C
Charge density on the metal kernels should be the same.

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D
Crystal lattice structures should have the same kind of unit cells.

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Solutions

An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other. Such alloys are formed by atoms with metallic radii that are within about 15 percent of each other. Because of similar radii and other characteristics of transition metals, alloys are readily formed by these metals. The alloys so formed are hard and have often high melting points.
Question 3/4
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Which of the following is the reason for stability of a Gd³⁺ion?

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A
4f orbital is completely filled.

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B
4f orbital is half filled.

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C
4f orbital has three unpaired electrons.

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D
4f orbital is completely vacant.

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Solutions

The reason for stability of a Gd³⁺ion is its half filled electronic configuration in 4f orbital.
The ground state configuration of Gadolinium (Gd) is [Xe] 4f⁷5d¹6s².
And configuration of Gd³⁺ion will be [Xe] 4f⁷5d⁰6s⁰. Thus, it will be stable.
Question 4/4
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Formulae of the compounds of lanthanoids are given below. Choose the one which is incorrect?

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A
Sulphides, Ln₂S₃

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B
Oxides, Ln₂O₃

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C
Hydroxides, Ln(OH)₃

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D
Nitrides, LnN₃

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Solutions

The correct formula is- LnN.

Question 1/4

Fe³⁺ + SCN^-

Fe²⁺ + [Fe(CN)₆]^3-

Ni²⁺ + NH₃

Cu²⁺ + SCN^-

Question 2/4

The difference in the atomic radii should be less than 15%.

Valence electronic configuration should be the same.

Charge density on the metal kernels should be the same.

Crystal lattice structures should have the same kind of unit cells.

Question 3/4

4f orbital is completely filled.

4f orbital is half filled.

4f orbital has three unpaired electrons.

4f orbital is completely vacant.

Question 4/4

Sulphides, Ln₂S₃

Oxides, Ln₂O₃

Hydroxides, Ln(OH)₃

Nitrides, LnN₃

Question 1/4

Fe3+ + SCN-

Fe2+ + [Fe(CN)6]3-

Ni2+ + NH3

Cu2+ + SCN-

Question 2/4

The difference in the atomic radii should be less than 15%.

Valence electronic configuration should be the same.

Charge density on the metal kernels should be the same.

Crystal lattice structures should have the same kind of unit cells.

Question 3/4

4f orbital is completely filled.

4f orbital is half filled.

4f orbital has three unpaired electrons.

4f orbital is completely vacant.

Question 4/4

Sulphides, Ln2S3

Oxides, Ln2O3

Hydroxides, Ln(OH)3

Nitrides, LnN3

Fe³⁺ + SCN^-

Fe²⁺ + [Fe(CN)₆]^3-

Ni²⁺ + NH₃

Cu²⁺ + SCN^-

Sulphides, Ln₂S₃

Oxides, Ln₂O₃

Hydroxides, Ln(OH)₃

Nitrides, LnN₃