Identify the diamagnetic octahedral complex ions from below $:$
$A. [Mn(CN)_6]^{3-}$
$B. [Co(NH_3)_6]^{3+}$
$C. [Fe(CN)_6]^{4-}$
$D. [Co(H_2O)_3F_3]$
Choose the correct answer from the options given below $:$

Number of stereoisomers possible for the octahedral complexes $[Co(NH_3)_3Cl_3]$ and $[Ni(en)_2Cl_2]$,respectively,are (where $en = 1,2-$ethylenediamine):

Consider the following low-spin complexes: $K_3[Co(NO_2)_6]$,$K_4[Fe(CN)_6]$,$K_3[Fe(CN)_6]$,$Cu_2[Fe(CN)_6]$,and $Zn_2[Fe(CN)_6]$. The sum of the spin-only magnetic moment values of complexes having yellow colour is $.......... B.M.$ (answer is nearest integer).

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 ions has the lowest magnetic moment?

The species that can have a $trans$-isomer is: ($en = \text{ethane-}1,2\text{-diamine}$,$ox = \text{oxalate}$)