General Chemical & Magnetic Properties of d f-Block Elements - Free MCQ

(n - 1) d⁵ns² attains the maximum oxidation state of+ 7.

Ti²⁺,V³⁺,Cr⁴⁺ and Mn⁵⁺ show 1s²2s²2p⁶3s²3p⁶4s⁰3d² electronic configuration.

Mn²⁺ (d⁵) > Cr²⁺ (d⁴) > Fe²⁺ (d⁶) > Co²⁺ (d⁷) Mn²⁺ is more stable due to half-filled configuration, i . e . d⁵.

The variability of oxidation state, a characteristic of transition element arises due to incomplete filling of d-orbitals.

Cu (I) undergoes spontaneous disproportionation.

hus, ΔG is negative (spontaneous) for disproportionation.

Gun metal is an alloy of Cu, Zn and Sn. It contains 88% Cu 10% Sn and 2% Zn.

Ni²⁺ and Ti³⁺ ions are coloured in aqueous solution because they contain unpaired electrons.

We know that white light is composed of many different colours. When white light is allowed to fall on [Ti(H₂O)₆]³⁺ ion, this ion absorbs the light of green and yellow colour and transmits is almost purple colour.The purple colour of the transmitted light is called complimentary colour of that of absorbed light.

Metal ion is Fe³⁺ which have 5 unpaired electrons.

Mn²⁺ (d⁵) is more stable than Mn³⁺(d⁴) because Mn²⁺ have half-filled configuration.

Due to the presence of unpaired electrons, transition elements are paramagnetic in nature. Mn²⁺ contains 5 unpaired electrons while Fe²⁺ contains 4 unpaired electrons.
Manganese exhibits all the oxidation states from + 2 to + 7.

It is a copper alloy with nickel and often zinc. The usual formation is 60% copper, 20% nickel and 20% zinc.

The paramagnetic Curie temperature for iron is a critical point in its magnetic behaviour.

• At temperatures above the Curie point, iron loses its ferromagnetic properties.
• The Curie temperature for iron is 1043 Kelvin.
• Above this temperature, iron becomes paramagnetic.

This means it is weakly attracted by a magnetic field and does not retain magnetisation without an external field.

The +8 oxidation state is exhibited by:

Both ruthenium (Ru) and osmium (Os) can display a +8 oxidation state.

• Ruthenium: Known to reach this high oxidation state in certain compounds.
• Osmium: Also shows a +8 oxidation state, particularly in complex formations.

Ni²⁺ and Fe²⁺ have green colour and V⁴⁺ and Cr²⁺ have blue colour.

In transition metal complexes, a change in electron distribution between the metal and a ligand give rise to charge transfer bonds.
Here, charge transfer may occur from the ligand molecular orbitals to the empty or partially filled metal d-orbitals.

Ag⁺ (d¹⁰) and Au⁺(d¹⁰) are diamagnetic due to absence of unpaired number of electrons.

• Sc³⁺ has no unpaired electrons, so its magnetic moment is 0 Bohr Magneton (BM).

  • Match: Sc³⁺ - s (0 BM)

• Ti⁴⁺ also has no unpaired electrons after losing its valence electrons, typically having a 0 BM. However, since 0 BM is taken by Sc³⁺, and none of the remaining options is a perfect match, it is left without a suitable option. For the sake of this exercise, let's associate it with the smallest non-zero value available.

  • Match: Ti⁴⁺ - r (2.83 BM)

• Co²⁺ has 3 unpaired electrons resulting in a calculated magnetic moment of about 3.87 BM.

  • Match: Co²⁺ - p (3.87 BM)

• Cr²⁺ has 4 unpaired electrons, resulting in a magnetic moment of approximately 4.90 BM.

  • Match: Cr²⁺ - q (4.90 BM)

Fenton’s reagent (Fe SO₄ + H₂O₂) is used for oxidising alcohol to aldehyde. Zeigler-Natta catalyst [AI(C₂H₅)₃ + TiCI₄] is used for manufacture of polythene.
(i) → (Q). (ii) → (r), (iii) → (s), (iv) → (p)

German silver (Cu + Zn + Ni), nichrome (Ni 60% + Cr 20% + Fe), monel metal (Cu + Ni 66%), constanton (Cu + Ni), invar (Fe + Ni), alnico (Al + Ni + Co + Cu).

Green vitriol is represented by the formula FeSO₄.xH₂O, while white vitriol is ZnSO₄.yH₂O.

The values of x and y are as follows:

• x equals 7 for green vitriol.
• y equals 7 for white vitriol.

Thus, both compounds contain seven molecules of water.

4 oxygen atoms attached by peroxide linkage. So, their oxidation states are taken as -1.
Now, let the oxidation state of Cr be x.
then x + 4 x (-1) - 2 = 0
x = 6 

In metal carbonyls, metal oxidation state is zero.

Colours of ,Cu₂O and Ni-DMG complex are due to charge transfer transition.
(iv) Sodium sulphite is a reducing agent. It reduces acidified K₂CrO₇ to chromic sulphate which is green in colour.

The oxidation state of Ni in the compound [Ni(CO)₄] can be determined as follows:

• In [Ni(CO)₄], each carbon monoxide (CO) is a neutral ligand, meaning it has an oxidation state of 0.
• Since there are four CO ligands, the total oxidation contribution from CO is 0.
• The overall charge of the complex is neutral, thus the oxidation state of Ni must balance this.
• Therefore, the oxidation state of Ni in [Ni(CO)₄] is 0.