The number of geometric isomers possible for the complex $[CoL_2 Cl_2]^{-}$ where $L = H_2NCH_2CH_2O^{-}$ is

$A$ chromium complex with a formula $CrCl_3 \cdot 6H_2O$ has a spin-only magnetic moment value of $3.87 \ BM$ and its solution conductivity corresponds to a $1:2$ electrolyte. $2.75 \ g$ of the complex was dissolved and passed through a cation exchanger. The solution obtained after the process was reacted with excess $AgNO_3$. The amount of $AgCl$ formed in the above process is . . . . . . $g$. (Nearest integer) [Given: Molar mass in $g \ mol^{-1}$: $Cr = 52, Cl = 35.5, Ag = 108, O = 16, H = 1$]

The complexes $[Co(NH_3)_6][Cr(C_2O_4)_3]$ and $[Cr(NH_3)_6][Co(C_2O_4)_3]$ exhibit which type of isomerism?

The metal ions that have the calculated spin-only magnetic moment value of $4.9 \ B.M.$ are:
$A. Cr^{2+}$ $B. Fe^{2+}$ $C. Fe^{3+}$ $D. Co^{2+}$ $E. Mn^{3+}$
Choose the correct answer from the options given below:

Among $(i) [Co(NH_3)_6]Cl_3$,$(ii) [Ni(NH_3)_6]Cl_2$,$(iii) [Cr(H_2O)_6]Cl_3$,$(iv) [Fe(H_2O)_6]Cl_2$,the complex which is diamagnetic is $....$

$A$ compound absorbs light in the wavelength region $490-500 \,nm$. Its complementary colour is