Which of the following types of isomerism is exhibited by $[Co(NH_3)_5(NO_2)](NO_3)_2$?
$i$. Optical
$ii$. Linkage
$iii$. Ionization
$iv$. Coordination

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

Which of the following compounds will exhibit coordination isomerism?

What is the spin-only magnetic moment value $(BM)$ of a divalent metal ion with atomic number $25$ in its aqueous solution?

Which of the following complexes exhibits the highest paramagnetic behaviour? (Where $gly = \text{glycine}$,$en = \text{ethylenediamine}$ and $bipy = \text{bipyridyl}$) (At. nos. $Ti = 22, V = 23, Cr = 24, Fe = 26, Co = 27$)

Although $Cr^{3+}$ and $Co^{2+}$ ions have the same number of unpaired electrons,why is the magnetic moment of $Cr^{3+}$ $3.87 \ B.M.$ and that of $Co^{2+}$ $4.87 \ B.M.?$