The different oxidation states exhibited by the lanthanoids are:

1.	+2, -3, +4	2.	-2, -3, -4
3.	+2, +3, -4	4.	+2, +3, +4

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 ${\mathrm{Mn}}^{3+},$ ${\mathrm{Cr}}^{3+},$ ${\mathrm{V}}^{3+,}$ $\mathrm{and}$ ${\mathrm{Ti}}^{3+ }$ are, respectively:

Alloy that contains lanthanoid metals is-

1. Mischmetal

2. Permalloy

3. Supermalloy

4. Brass

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

The number of 3d electrons in the Cr³⁺ ions will be:

The correct statement regarding Ag is 

The enthalpy of atomization of transition metals is high due to :

1. High effective nuclear charge

2. A large number of valence electrons

3. Very strong metallic bonds

4. All of the above