Co-ordination Compounds MCQs for NEET — Chemistry Questions with Answers

Potassium ferrocyanide ($K_4[Fe(CN)_6]$) is diamagnetic because it has no unpaired electrons in its low-spin complex. However, potassium ferricyanide ($K_3[Fe(CN)_6]$) is paramagnetic because it contains unpaired electrons in its high-spin complex. The assertion is false because potassium ferricyanide is not diamagnetic, and the reason is also false as it states that both have unpaired electrons. Thus, the correct answer is o4: If the assertion and reason both are false.

The assertion that $[Ti(H_2O)_6]^{3+}$ is colored while $[Sc(H_2O)_6]^{3+}$ is colorless is true. The reason is also true: d-d transition is not possible in $[Sc(H_2O)_6]^{3+}$ because Scandium in the +3 oxidation state has an electron configuration of $[Ar]3d^0$, meaning there are no d-electrons to undergo d-d transitions, which are responsible for the color. Therefore, both the assertion and reason are true, and the reason correctly explains the assertion. The correct option is o1.

I - 131 is used for treatment of thyroid disorders.

The formula for iron (III) hexacyanoferrate (II) is $ Fe_4[Fe(CN)_6]_3 $. In this compound, iron exists in two oxidation states: Fe(III) and Fe(II). The hexacyanoferrate (II) ion is $ [Fe(CN)_6]^{4-} $, and when combined with Fe(III) ions, the overall formula becomes $ Fe_4[Fe(CN)_6]_3 $.

(C).  Sodium hexametaphosphate$-$a polyphosphate, combines with cations $\left(\mathrm{i}.\mathrm{e}., {\mathrm{Ca}}^{2+}, {\mathrm{Mg}}^{2+}\right)$ to

        form soluble complexes.

            $$\begin{gathered} 2{\mathrm{Ca}}^{2+}+{\mathrm{Na}}_2\left[{\mathrm{Na}}_4{\left({\mathrm{PO}}_3\right)}_6\right]\to 4{\mathrm{Na}}^{+}+{\mathrm{Na}}_2\left[{\mathrm{Ca}}_2{\left({\mathrm{PO}}_3\right)}_6\right] \\ \mathrm{complex} \left(\mathrm{soluble}\right) \end{gathered}$$

The diamond unit cell is a face-centered cubic (FCC) structure with 8 carbon atoms at the corners of the cube. Each carbon atom is shared by 8 neighboring cubes, so the total number of carbon atoms per unit cell is 8.