The total possible coordination isomers for the following compounds respectively are :
$[Co(en)_3] [Cr(C_2O_4)_3]$
$[Cu(NH_3)_4] [CuCl_4]$
$[Ni(en)_3] [Co(NO_2)_6]$

Which isomer of $CrCl_3 \cdot 6H_2O$ is green in color and reacts with $AgNO_3$ to form one mole of $AgCl$?

For which of the following configurations is the spin-only magnetic moment value $2.84 \ BM$?

In an experiment,$m$ grams of a compound $X$ (gas/liquid/solid) taken in a container is loaded in a balance as shown in figure $I$ below. In the presence of a magnetic field,the pan with $X$ is either deflected upwards (figure $II$),or deflected downwards (figure $III$),depending on the compound $X$. Identify the correct statement$(s)$:
$(A)$ If $X$ is $H_2O_{(l)}$,deflection of the pan is upwards.
$(B)$ If $X$ is $K_4[Fe(CN)_6]_{(s)}$,deflection of the pan is upwards.
$(C)$ If $X$ is $O_{2(g)}$,deflection of the pan is downwards.
$(D)$ If $X$ is $C_6H_{6(l)}$,deflection of the pan is downwards.

Which of the following does not show optical isomerism?
$(en = \text{ethylenediamine})$

The complex,$[Pt(Py)(NH_3)BrCl]$,will have how many geometrical isomers?