d- and f-Block Elements

Which one of the elements with the following outer orbital configurations may exhibit the largest number of oxidation states?

1. 3d54s1
2. 3d54s2
3. 3d24s2
4. 3d34s2

Out of TiF62-, CoF63-, Cu2Cl2 and NiCl42- (Z of Ti = 22, Co = 27, Cu = 29, Ni = 28) the colourless species are

1. Cu2Cl2 and NiCl42-
2. TiF62- and Cu2Cl2
3. CoF63- and NiCl42-
4. TiF62- and CoF63-

The correct order of decreasing second ionisation enthalpy of Ti(22), V(23), Cr(24) and Mn(25) is

1. Mn > Cr > Ti > V
2. Ti > V > Cr > Mn
3. Cr > Mn > V > Ti
4. V > Mn > Cr > Ti

Which one of the following ions is the most stable in aqueous solution? (At. No. Ti = 22, V = 23, Cr = 24, Mn = 25)

1. V3+
2. Ti3+
3. Mn3+
4. Cr3+

Identify the incorrect statement among the following:

1. Lanthanoid contraction is the accumulation of successive shrinkages.
2. As a result of lanthanoid contraction, the properties of 4d series of the transition elements have no similarities with the 5d series of elements.
3. Shielding power of 4f electrons is quite weak.
4. There is a decrease in the radii of the atoms or ions as one proceeds from La to Lu.

In which of the following pairs are both the ions coloured in aqueous solution? (At. no. : Sc = 21, Ti = 22, Ni = 28, Cu = 29, Co = 27)

1. Ni2+, Cu+
2. Ni2+, Ti3+
3. Sc3+, Ti3+
4. Sc3+, Co2+.

Copper sulphate dissolves in excess of KCN to give

1. Cu(CN)2
2. CuCN
3. [Cu(CN)4]3-
4. [Cu(CN)4]2-

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

1. more active nature of the actinoids
2. more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
3. lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
4. greater metallic character of the lanthanoids than that of the corresponding actinoids.

More number of oxidation states are exhibited by the actinoids than by the lanthanoids. The main reason for this is

1. more active nature of the actinoids
2. more energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
3. lesser energy difference between 5f and 6d orbitals than that between 4f and 5d orbitals
4. greater metallic character of the lanthanoids than that of the corresponding actinoids.

The number of moles of KMnO4 reduced by one mole of KI in alkaline medium is

1. one
2. two
3. five
4. one fifth