NEET UG 2025 — Physical Chemistry

$\begin{aligned} &\text { Consider the following compounds: }\\ &\mathrm{\underline{K}O}_2, \mathrm{H}_2 \mathrm{\underline{O}}_2 \text { and } \mathrm{H}_2 \mathrm{\underline{S}O}_4 \text {. } \end{aligned}$ The oxidation states of the underlined elements in them are, respectively,

5 moles of liquid X and 10 moles of liquid Y make a solution having a vapour pressure of 70 torr. The vapour pressures of pure X and Y are 63 torr and 78 torr respectively. Which of the following is true regarding the described solution?

For the reaction $\mathrm{A}(\mathrm{g}) \rightleftharpoons 2 \mathrm{~B}(\mathrm{~g})$, the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500 , at 1000 K . [Given : $\mathrm{R}=0.0831 \mathrm{~L} \mathrm{~atm} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ ] $\mathrm{K}_{\mathrm{p}}$ for the reaction at 1000 K is

Which of the following aqueous solution will exhibit highest boiling point?

Dalton's Atomic theory could not explain which of the following?

Energy and radius of first Bohr orbit of $\mathrm{He}^{+}$and $\mathrm{Li}^{2+}$ are [Given $\mathrm{R}_{\mathrm{H}}=2.18 \times 10^{-18} \mathrm{~J}, \mathrm{a}_0=52.9 \mathrm{pm}$ ]

Among the following choose the ones with equal number of atoms. A. 212 g of $\mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~s})$ [molar mass $=106 \mathrm{~g}$ ] B. 248 g of $\mathrm{Na}_2 \mathrm{O}$ (s) [molar mass $=62 \mathrm{~g}$ ] C. 240 g of $\mathrm{NaOH}(\mathrm{s})$ [molar mass $=40 \mathrm{~g}]$ D. 12 g of $\mathrm{H}_2(\mathrm{~g})$ [molar mass $=2 \mathrm{~g}$ ] E. 220 q of $\mathrm{CO}_2(\mathrm{q})$ [molar mass $\left.=44 \mathrm{~g}\right]$ Choose the correct answer from the options given below:

Higher yield of NO in $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ can be obtained at [ $\Delta \mathrm{H}$ of the reaction $=+180.7 \mathrm{~kJ} \mathrm{~mol}^{-1}$ ] A. higher temperature B. lower temperature C. higher concentration of $\mathrm{N}_2$ D. higher concentration of $\mathrm{O}_2$ Choose the correct answer from the options given below :

If the molar conductivity $\left(\Lambda_{\mathrm{m}}\right)$ of a $0.050 \mathrm{~mol} \mathrm{~L}^{-1}$ solution of a monobasic weak acid is $90 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$, its extent (degree) of dissociation will be [Assume $\Lambda_{+}^{\circ}=349.6 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and $\left.\Lambda_{-}^{\circ}=50.4 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}.\right]$

Phosphoric acid ionizes in three steps with their ionization constant values $\mathrm{K}_{\mathrm{a}_1}, \mathrm{~K}_{\mathrm{a}_2}$ and $\mathrm{K}_{\mathrm{a}_3}$, respectively, While K is the overall ionization constant. Which of the following statements are true? A. $\log \mathrm{K}=\log \mathrm{K}_{\mathrm{a}_1}+\log \mathrm{K}_{\mathrm{a}_2}+\log \mathrm{K}_{\mathrm{a}_3}$ B. $\mathrm{H}_3 \mathrm{PO}_4$ is a stronger acid than $\mathrm{H}_2 \mathrm{PO}_4^{-}$and $\mathrm{HPO}_4^{2-}$ C. $K_{a_1}\gt K_{a_2}\gt K_{a_3}$ D. $\mathrm{K}_{\mathrm{a}_1}=\frac{\mathrm{K}_{\mathrm{a}_3}+\mathrm{K}_{\mathrm{a}_2}}{2}$ Choose the correct answer from the options given below:

If the rate constant of a reaction is $0.03 \mathrm{~s}^{-1}$, how much time does it take for $7.2 \mathrm{~mol} \mathrm{~L}^{-1}$ concentration of the reactant to get reduced to $0.9 \mathrm{~mol} \mathrm{~L}^{-1}$ ? (Given $: \log 2=0.301$ )

The ratio of the wavelengths of the light absorbed by a Hydrogen atom when it undergoes $\mathrm{n}=2 \rightarrow \mathrm{n}=3$ and $\mathrm{n}=4 \rightarrow \mathrm{n}=6$ transitions, respectively, is

$\mathrm{C}(\mathrm{~s})+2 \mathrm{H}_2(\mathrm{~g}) \rightarrow \mathrm{CH}_4(\mathrm{~g}) ; \Delta \mathrm{H}=-74.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$ Which of the following diagrams gives an accurate representation of the above reaction? $[\mathrm{R} \rightarrow$ reactants; $\mathrm{P} \rightarrow$ products $]$

The conjugate base of H₂SO₄ is:

If the half-life $\left(\mathrm{t}_{1 / 2}\right)$ for a first order reaction is 1 minutes, then the time required for $99.9 \%$ completion of the reaction is closest to:

Match List - I with List - II $\begin{array}{llll} & \begin{array}{l} \text { List-I } \\ \text { (Example) } \end{array} & & \begin{array}{l} \text { List-II } \\ \text { (Type of Solution) } \end{array} \\ \text { A. } & \text { Humidity } & \text { I. } & \text { Solid in solid } \\ \text { B. } & \text { Alloys } & \text { II. } & \text { Liquid in gas } \\ \text { C. } & \text { Amalgams } & \text { III. } & \text { Solid in gas } \\ \text { D. } & \text { Smoke } & \text { IV. } & \text { Liquid in solid } \end{array}$ Choose the correct answer from the options given below:

The standard heat of formation, in $\mathrm{kcal} / \mathrm{mol}^{\text {of }} \mathrm{Ba}^{2+}$ is : [Given : standard heat of formation of $\mathrm{SO}_4^{2-}$ ion (aq) $=-216 \mathrm{kcal} / \mathrm{mol}$, Standard heat of crystallisation of $\mathrm{BaSO}_4(\mathrm{~s})=-4.5 \mathrm{kcal} / \mathrm{mol}$, standard heat of formation of $\left.\mathrm{BaSO}_4(\mathrm{~s})=-349 \mathrm{kcal} / \mathrm{mol}\right]$