Observe the following sets \begin{array}{|l|l|l|}\hline & {|c|}{ Order } & {c|}{ Property } \\\hline i. &…

Observe the following sets \begin{array}{|l|l|l|}\hline & {|c|}{ Order } & {c|}{ Property } \\\hline i. & \mathrm{NH}_3>\mathrm{H}_2 \mathrm{O}>\mathrm{SO}_2 & Bond angle \\\hline ii. & \mathrm{H}_2 \mathrm{O}>\mathrm{NH}_3>\mathrm{H}_2 \mathrm{~S} & Dipole moment \\\hline iii. & \mathrm{N}_2>\mathrm{O}_2>\mathrm{H}_2 & Bond enthalpy \\\hline iv. & \mathrm{NO}^{+}>\mathrm{O}_2>\mathrm{O}_2^{2-} & Bond order \\\hline\end{array} Which of the above sets are correctly matched?
  1. i, ii, iv only
  2. ii, iii only
  3. ii, iii, iv only
  4. i, iii, iv only

Solution

(i)
In $\mathrm{NH}_3$ and $\mathrm{H}_2 \mathrm{O}$ bond angle should be $109.28^{\circ}$ but in ammonia there is a lone pair-bond pair repulsion and in $\mathrm{H}_2 \mathrm{O}$ two lone pair and bond pair repulsion which decrease the bond angle. $\mathrm{SO}_2$ has planar structure and its bond angle should be $120^{\circ}$ but due to lone-pair-bond pair repulsion it decreases. $\therefore \quad \mathrm{SO}_2 \gt \mathrm{NH}_3 \gt \mathrm{H}_2 \mathrm{O}$ (ii)
Dipole moment $\propto$ Electronegativity Oxygen is more electronegative than nitrogen so dipole moment of $\mathrm{H}_2 \mathrm{O}$ is more as compare to $\mathrm{NH}_3$ and $\mathrm{H}_2 \mathrm{~S}$ $\mathrm{H}_2 \mathrm{O} \gt \mathrm{NH}_3 \gt \mathrm{H}_2 \mathrm{~S}$ (iii) More the bond order more will be the bond enthalpy $\begin{array}{|c|c|}\hline \text{Molecule} & \text{Bond-order} \\ \hline \mathrm{N}_2 & 3 \\ \hline \mathrm{O}_2 & 2 \\ \hline \mathrm{H}_2 & 1 \\ \hline\end{array}$ $\therefore$ Bond enthalpy $\mathrm{N}_2 \gt \mathrm{O}_2 \gt \mathrm{H}_2$ (iv) $\begin{array}{|c|c|}\hline \text{Molecule} & \text{Bond order} \\ \hline \mathrm{NO}^{+} & 2.5 \\ \hline \mathrm{O}_2 & 2 \\ \hline \mathrm{O}_2{ }^{2-} & 1 \\ \hline\end{array}$
Bond order $\mathrm{NO}^{+}\gt\mathrm{O}_2\gt\mathrm{O}_2{ }^{2-}$ $\therefore$ (ii), (iii) and (iv) are correct.

Asked in: AP EAMCET 2024 (21 May Shift 1)

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