d- and f-Block Elements

The reason for greater range of oxidation states in actinoids is attributed to

1. actinoid contraction
2. 5f, 6d and 7s levels having comparable energies
3. 4f and 5d levels being close in energies
4. the radioactive nature of actinoids.

Which one of the following statements is correct when SO2 is passed through acidified K2Cr2O7 solution?

1. SO2 is reduced.
2. Green Cr2(SO4)3 is formed.
3. The solution turns blue.
4. The solution is decolourised.

The electronic configuration of Eu (Atomic No. 63), Gd (Atomic No. 64) and Tb (Atomic No. 65) are

1. [Xe]4f6 5d1 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f8 5d1 6s2
2. [Xe]4f7 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f9 6s2
3. [Xe]4f7 6s2, [Xe]4f8 6s2 and [Xe]4f8 5d1 6s2
4. [Xe]4f6 5d1 6s2, [Xe]4f7 5d1 6s2 and [Xe]4f9 6s2

Which one of the following statements related to lanthanoids is incorrect?

1. Europium shows +2 oxidation state.
2. The basicity decreases as the ionic radius decreases from Pr to Lu.
3. All the lanthanons are much more reactive than aluminium.
4. Ce(+4) solutions are widely used as oxidizing agent in volumetric analysis.

Gadolinium belongs to 4f series. Its atomic number is 64. Which of the following is the correct electronic configuration of gadolinium?

1. [Xe]4f9 5s1
2. [Xe]4f7 5d1 6s2
3. [Xe]4f6 5d2 6s2
4. [Xe]4f8 6d2

Magnetic moment 2.84 B.M. is given by (At. nos. Ni = 28, Ti = 22, Cr = 24, Co = 27)

1. Cr2+
2. Co2+
3. Ni2+
4. Ti3+

Because of lanthanoid contraction, which of the following pairs of elements have nearly same atomic radii? (Numbers in the parenthesis are atomic numbers)

1. Zr(40) and Hf(72)
2. Zr(40) and Ta(73)
3. Ti(22) and Zr(40)
4. Zr(40) and Nb(41)

The reaction of aqueous KMnO4 with H2O2 in acidic conditions gives

1. Mn4+ and O2
2. Mn2+ and O2
3. Mn2+ and O3
4. Mn4+ and MnO2

Magnetic moment 2.83 BM is given by which of the following ions? (At. nos. Ti = 22, Cr = 24, Mn = 25, Ni = 28)

1. Ti3+
2. Ni2+
3. Cr3+
4. Mn2+

Reason of lanthanoid contraction is

1. negligible screening effect of 'f'-orbitals
2. increasing nuclear charge
3. decreasing nuclear charge
4. decreasing screening effect.