1

### JEE Main 2016 (Online) 10th April Morning Slot

Which of the following is an example of homoleptic complex ?
A
[Co(NH3)6]Cl3
B
[Pt(NH3)2Cl2]
C
[Co(NH3)4Cl2]
D
[Co(NH3)5Cl]Cl2
2

### JEE Main 2017 (Offline)

On treatment of 100 mL of 0.1 M solution of CoCl3. 6H2O with excess AgNO3; 1.2 $\times$ 1022 ions are precipitated. The complex is:
A
[Co(H2O)3Cl3].3H2O
B
[Co(H2O)6]Cl3
C
[Co(H2O)5Cl]Cl2.H2O
D
[Co(H2O)4Cl2]Cl.2H2O

## Explanation

Moles of complex = ${{Molarity \times Volume\left( {mL} \right)} \over {1000}}$

= ${{100 \times 0.1} \over {1000}}$ = 0.01 mole

Moles of ions precipitated with excess of AgNO3

= ${{1.2 \times {{10}^{22}}} \over {6.023 \times {{10}^{23}}}}$ = 0.02 mole

So 0.01 × n = 0.02

$\Rightarrow$ n = 2

It means 2Cl ions present in ionization sphere.

$\therefore$ The formula of complex is [Co(H2O)5Cl]Cl2.H2O
3

### JEE Main 2017 (Online) 8th April Morning Slot

The pair of compounds having metals in their highest oxidation state is :
A
MnO2 and CrO2Cl2
B
[NiCl4]2$-$ and [CoCl4]2$-$
C
[Fe(CN)6]3$-$ and [Cu(CN)4]2$-$
D
[FeCl4]$-$ and Co2O3
4

### JEE Main 2017 (Online) 9th April Morning Slot

[Co2(CO)8] displays :
A
one Co−Co bond, six terminal CO and two bridging CO
B
one Co−Co bond, four terminal CO and four bridging CO
C
no Co−Co bond, six terminal CO and two bridging CO
D
no Co−Co bond, four terminal CO and four bridging CO