Chemical Bonding · JEE Advanced previous year questions

2025 3 questions

1. Q382025 · 18 May 2025 · Paper 1· One or more correct

   The pair(s) of diamagnetic ions is(are)

   1. A.$\mathrm{L}{\mathrm{a}}^{3+},\mathrm{C}{\mathrm{e}}^{4+}$
   2. B.$\mathrm{Y}{\mathrm{b}}^{2+},\mathrm{L}{\mathrm{u}}^{3+}$
   3. C.$\mathrm{L}{\mathrm{a}}^{2+},\mathrm{C}{\mathrm{e}}^{3+}$
   4. D.$\mathrm{Y}{\mathrm{b}}^{3+},\mathrm{L}{\mathrm{u}}^{2+}$
   Show answer

   Answer: A, B

2. Q392025 · 18 May 2025 · Paper 1· One or more correct

   For the reaction sequence given below, the correct statement(s) is(are) Cyclohexene $\stackrel{\text{HBr}}{\to }$ $\mathbf{P}$; $\mathbf{P}$ $\stackrel{\text{Finkelstein reaction}}{\to }$ $\mathbf{Q}$; $\mathbf{P}$ $\stackrel{\text{Swarts reaction}}{\to }$ $\mathbf{R}$ (In the options, X is any atom other than carbon and hydrogen, and it is different in $\mathbf{P}$, $\mathbf{Q}$ and $\mathbf{R}$)

   1. A.C–X bond length in $\mathbf{P}$, $\mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{Q}>\mathbf{R}>\mathbf{P}$.
   2. B.C–X bond enthalpy in $\mathbf{P}$, $\mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{R}>\mathbf{P}>\mathbf{Q}$.
   3. C.Relative reactivity toward ${\mathrm{S}}_{\mathrm{N}}2$ reaction in $\mathbf{P}$, $\mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{P}>\mathbf{R}>\mathbf{Q}$.
   4. D.$\mathrm{p}{K}_{\mathrm{a}}$ value of the conjugate acids of the leaving groups in $\mathbf{P}$, $\mathbf{Q}$ and $\mathbf{R}$ follows the order $\mathbf{R}>\mathbf{Q}>\mathbf{P}$.
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   Answer: B

3. Q372025 · 18 May 2025 · Paper 2· One or more correct

   The correct statement(s) about intermolecular forces is(are)

   1. A.The potential energy between two point charges approaches zero more rapidly than the potential energy between a point dipole and a point charge as the distance between them approaches infinity.
   2. B.The average potential energy of two rotating polar molecules that are separated by a distance $r$ has $1/r^3$ dependence.
   3. C.The dipole-induced dipole average interaction energy is independent of temperature.
   4. D.Nonpolar molecules attract one another even though neither has a permanent dipole moment.
   Show answer

   Answer: C, D