Which of the following ligands is able to form linkage isomers?

$[Fe(NO_2)_3Cl_3]$ and $[Fe(ONO)_3Cl_3]$ show:

Which of the following pairs of complexes are isomeric with each other but their aqueous solutions exhibit different molar conductivities?

The one that is not expected to show isomerism is:

The existence of two different coloured complexes with the composition of $[Co(NH_3)_4Cl_2]^+$ is due to

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.