Physical Chemistry PYQ

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 $\left.\mathrm{BaSO}_4(\mathrm{~s})=-349 \mathrm{kcal} / \mathrm{mol}\right]$

$\begin{aligned} &\text { Consider the following compounds: }\\ &\mathrm{\underline{K}O}_2, \mathrm{H}_2 \mathrm{\underline{O}}_2 \text { and } \mathrm{H}_2 \mathrm{\underline{S}O}_4 \text {. } \end{aligned}$ 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:

Given below are two statements: Statement I: The Balmer spectral line for $H$ atom with lowest energy is locateld at $\frac{5}{36} R_H \mathrm{~cm}^{-1}$. $\left(\mathrm{R}_{\mathrm{H}}=\right.$ Rydberg constant $)$ Statement II: When the temperature of blackbody increases, the maxima of the curve (intensity and wavelength) shifts to shorter wavelength. In the light of the above statements, choose the correct answer from the options given below:

1 gram of sodium hydroxide was treated with 25 mL of 0.75 M HCl solution, the mass of sodium hydroxide left unreacted is equal to

The ratio of solubility of AgCl in 0.1 M KCl solution to the solubility of AgCl in water is: (Given : Solubility product of $\mathrm{AgCl}=10^{-10}$ )

The pH of a solution is defined as:

Choose the correct statement for the work done in the expansion and heat absorbed or released when 5 litres of an ideal gas at 10 atmospheric pressure isothermally expands into vacuum until volume is 15 litres: