Mn²⁺ compounds are more stable than Fe²⁺ compounds towards oxidation in their +3 state because :

The +2 oxidation state becomes more stable in the first half of the first-row transition elements with increasing atomic number because:

1. s-orbital is becoming more and more half-filled.

2. f-orbital is becoming more and more half-filled.

3. d-orbital is becoming more and more half-filled.

4. p-orbital is becoming more and more half-filled.

The oxo metal anions of the 3d series in which the metal exhibits an oxidation state equal to its group number is /are -

1. ${\mathrm{VO}}_3^{-}$

2. ${\mathrm{CrO}}_4^{2-}$

3. ${\mathrm{MnO}}_4^{-}$

4. All of the above.

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

The d-block elements that may not be regarded as transition elements are :

What is the electronic configuration of transition elements?

1. (n − 1)d^1-10 ns^0-2 

2. (n − 1)d^1-10 ns²

3. nf² np^1-6

4. nd² np^1-6

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:

1. Mn

2. Cu

3. Fe

4. Zn

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: