1

JEE Main 2018 (Online) 16th April Morning Slot

In Wilkinson's catalyst, the hybridization of central metal ion and its shape are respectively :
A
sp3d, trigonal bipyramidal
B
sp3, tetrahedral
C
dsp2, square planar
D
d2sp3, octahedral

Explanation

Wilkinson's catalyst is [RhCl(PPh3)3]

Here central atom is Rh.

Oxidation state of Rh here is = + 1

$\therefore$   Electronic configuration of Rh+ = [Kr]4d8

And the complex is square planar

2

JEE Main 2018 (Online) 16th April Morning Slot

Which of the following complexes will shows geometrical isomerism ?
A
aquachlorobis (ethylenediamine) cobalt (II) chloride
B
pentaaquachlorohromium (III) chloride
C
potassium amminetrichloropltinate (II)
D
potassium tris(oxalato) chromate (III)

Explanation

(a)   [Co(H2O) Cl(en)2]Cl  $\to$  it shows gemetrical isomerism.

(b)   [Cr(H2O)5Cl]Cl2  :   This complex is [MA5B] type. It does not show geometrical isomerism.

(c)   K[Pt(NH3)Cl3]  :  Thiscomplex is [MAB3] type. It does not show geometrical isomerism.

(d)   K3[Cr(OX)3]  :  This complex is [M(AA)3] type. It does not show geometrical isomerism.
3

JEE Main 2019 (Online) 9th January Morning Slot

Two complexes [Cr(H2O)6]Cl3 (A) and [Cr(NH3)6]Cl3 (B) are violet and yellow coloured, respectively. The incorrect statement regarding them is :
A
$\Delta$0 values of (A) and (B) are calculated from the energies of violet and yellow light, respectively
B
both are paramagnetic with three unpaired electrons
C
both absorb energies corresponding to their complementry colors.
D
$\Delta$0 value for (A) is less than that of (B).

Explanation

NH3 is a strong field ligand.

H2O is weak field ligand.

Let $\Delta$violet is the crystal field splitting energy of complex A and $\Delta$yellow is for complex B.

$\therefore$   $\Delta$yellow > $\Delta$violet.

We know, $\Delta$ = ${{hc} \over {{\lambda _{absorb}}}}$

Violet color will absorb yellow color and yellow color will absorb violet color.

$\therefore$   $\Delta$yellow = ${{hc} \over {{\lambda _{violet}}}}$

and $\Delta$violet = ${{hc} \over {{\lambda _{yellow}}}}$

So, $\Delta$o of A is calculated from energy of yellow light and $\Delta$o of B is calculated from energy of violet light.
4

JEE Main 2019 (Online) 9th January Evening Slot

The complex that has highest crystal field splitting energy ($\Delta$), is :
A
[Co(NH3)5(H2O)]Cl3
B
K2[CoCl4]
C
[Co(NH3)5Cl]Cl2
D
K3[Co(CN)6]

Explanation

As complex K3[Co(CN)6] have CN$-$ ligand which is strongfield ligand amongst the given ligands in other complexes.