The consequence(s) of lanthanoid contraction is/are :  

1.	Similarity in the properties of second and third transition series.
2.	Separation of lanthanoids is difficult.
3.	Variation in the basic strength of lanthanide hydroxides.
4.	All of the above.

Which d-block elements are not considered transition elements, and why?

The different oxidation states exhibited by the lanthanoids are:

The "Disproportionation" reaction means that :

In the 3d series, a metal with a +1 oxidation state is:

The number of unpaired electrons in the gaseous ions ${\mathrm{Mn}}^{3+},$ ${\mathrm{Cr}}^{3+},$ ${\mathrm{V}}^{3+,}$ $\mathrm{and}$ ${\mathrm{Ti}}^{3+\hspace{0.17em}}$ are, respectively:

Alloy that contains lanthanoid metals is-

Give below are some atomic numbers:

29, 59, 74, 95, 102, 104
The atomic numbers of the inner transition elements among the above are :

The electronic configuration of the last element of actinoids is :

1. Thorium, Th: $\left[\mathrm{Rn}\right]5{\mathrm{f}}^{14}6{\mathrm{d}}^{1}7{\mathrm{s}}^2$

2. Lawrencium, Lr: $\left[\mathrm{Rn}\right]5{\mathrm{f}}^{14}6{\mathrm{d}}^{1}7{\mathrm{s}}^2$

3. Neptunium, Np: $\left[\mathrm{Rn}\right]5{\mathrm{f}}^{14}6{\mathrm{d}}^{1}7{\mathrm{s}}^2$

4. Protactinium, Pa: $\left[\mathrm{Rn}\right]5{\mathrm{f}}^{14}6{\mathrm{d}}^{1}7{\mathrm{s}}^2$