The electronic configuration of Platinum (atomic number: 78) is:

With F highest stable oxidation state of Mn is

1. +6

2. +4

3. +7

4. +3

The correct order of the following elements with respect to their density is-

1. Cr < Zn < Co < Cu < Fe

2. Zn < Cu < Co < Fe < Cr

3. Zn < Cr < Fe < Co < Cu

4. Cr < Fe < Co < Cu < Zn

The correct statement is

(1) Green vitriol and blue vitriol are isomorphous

(2) KMnO₄ and K₂Cr₂O₇ are coloured due to d-d transitions

(3) Cu₂Cl₂ and Ag₂S are coloured

(4) Upon strong heating paramagnetic gases are evolved by CuSO₄ and AgNO₃

$\mathrm{Fe}+{\mathrm{H}}_2\mathrm{O}\stackrel{1023-1073\mathrm{K}}{\to } \mathrm{Product}$
$\left(\mathrm{Steam}\right)$
$\mathrm{Product} \mathrm{formed} \mathrm{is}$
$1. \mathrm{FeO}+{\mathrm{H}}_2$

2. ${\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{H}}_2\mathrm{O}$

3. ${\mathrm{Fe}}_2{\mathrm{O}}_3+{\mathrm{H}}_2$

4. ${\mathrm{Fe}}_3{\mathrm{O}}_4+{\mathrm{H}}_2$

Which of the following has the highest negative $\left(\raisebox{1ex}{${\mathrm{M}}^{2+}$}\!\left/ \!\raisebox{-1ex}{$\mathrm{M}$}\right.\right)$ standard electrode potential ?

1. Ti

2. Cu

3. Mn

4. Zn

The incorrect statement about transition elements is: 

1. The most stable oxidation state is +3 and its stability increases across the period.

2. Transition elements of 3d-series atomic sizes increase from Cr to Cu.

3. Examples of alloys of transition metals with non-transition metals are brass (copper-zinc) and bronze (copper-tin).

4. Some transition elements like Ni, Fe, and Cr may show zero oxidation state in some of their compounds.

Which of the following explains the primary cause of lanthanoid contraction?