The pair of compounds that can exist together is:

1. FeCl₃, SnCl₂

2. HgCl₂, SnCl₂

3. FeCl₂, SnCl₂

4. FeCl₃, Kl

The reason for the lanthanoid contraction is:

1. negligible screening effect of 'f' orbitals.

2. increasing nuclear charge.

3. decreasing nuclear charge.

4. decreasing screening effect.

Which of the following statements is false? 

1.  Fe>Mn>Co>Cr

2.  Co>Mn>Fe>Cr

3.  Cr>Mn>Co>Fe

4.  Mn>Fe>Cr>Co

Acidified K₂Cr₂O₇ solution turns green when Na₂SO₃ is added to it. This is due to the formation of:

1.  ${\mathrm{CrO}}_4^{2-}$

2.  ${\mathrm{Cr}}_2{\left({\mathrm{SO}}_3\right)}_3$

3.  ${\mathrm{CrSO}}_4$

4.  ${\mathrm{Cr}}_2{\left({\mathrm{SO}}_4\right)}_3$

Which of the following ions will exhibit colour in aqueous solutions?

1. La³⁺ (Z=57)

2. Ti³⁺ (Z=22)

3. Lu³⁺ (Z=71)

4. Sc³⁺ (Z=21)

Which one of the following ions has electronic configuration [Ar] 3d⁶? 
(At. no :Mn = 25, Fe= 26, Co= 27, Ni = 28)

1. $N{i}^{3+}$

2. $M{n}^{3+}$

3. $F{e}^{3+}$

4. $C{o}^{3+}$