Chemistry MCQs for NEET — Practice Questions with Answers

The compound $[Co(NH_3)_5NO_2]Cl_2$ does not show geometrical isomerism because it contains only one bidentate ligand (NO2), and the positions of the ligands around the central metal ion do not allow for geometrical isomers. Geometrical isomerism typically occurs in complexes with at least two different types of ligands that can occupy different spatial arrangements around the central metal ion.

The complex $[Cr(NH_3)_6][Co(CN)_6]$ can exhibit coordination isomerism. In coordination isomerism, the composition of the coordination entities (complex ions) is interchangeable between the cation and anion. Thus, $[Cr(NH_3)_6][Co(CN)_6]$ can have its metal ions swap places to form $[Co(NH_3)_6][Cr(CN)_6]$.

The compounds $[Co(NH_3)_5NO_2]Cl_2$ and $[Co(NH_3)_5(ONO)]Cl_2$ are related to each other as linkage isomers. Linkage isomerism occurs when a ligand can coordinate to the metal ion through two different atoms. In this case, the nitrite ligand (NO2) can bind through the nitrogen atom (NO2) or the oxygen atom (ONO).

The compounds $[Co(NH_3)_5Br]SO_4$ and $[Co(NH_3)_5SO_4]Br$ are examples of ionisation isomerism. This type of isomerism occurs when the counter ion in a complex salt is itself a potential ligand and can displace the ligand within the coordination sphere to give a different ionisable species.

$[Co(NH_3)_5 Br]SO_4$ exhibits ionisation isomerism. Ionisation isomerism occurs when an ionisable counter ion such as SO_4^{2-} or Br^- is swapped with a ligand in the coordination sphere, leading to different compounds that ionise to give different ions in solution.

Among the given options, $[Fe(H_2O)_6]^{+2}$ has the highest paramagnetism. This is because it has the maximum number of unpaired electrons compared to the other ions listed. Iron(II) in $[Fe(H_2O)_6]^{+2}$ has 4 unpaired electrons (d^6 configuration), making it the most paramagnetic.

The compound nitro pentamine chromium (III) chloride exhibits linkage isomerism. This is because the nitro group (NO2) can bind to the metal center either through the nitrogen atom (nitro) or through the oxygen atom (nitrito), leading to two different isomers.

The complex compound $[Co(NH_3)_3 (NO_2)_3]$ is a poor electrolytic conductor in solution because it does not dissociate into ions easily. Unlike ionic compounds, which dissociate to give ions that conduct electricity, this complex remains largely intact in solution, thereby conducting electricity poorly.

Paramagnetism is due to the presence of unpaired electrons. In $[NiCl_4]^{2–}$, nickel is in the +2 oxidation state and has the electronic configuration 3d^8. Chloride ions are weak field ligands and do not cause pairing of electrons. Therefore, $[NiCl_4]^{2–}$ has two unpaired electrons, making it paramagnetic.