Physical Chemistry PYQ — Page 65

If $m$ and $e$ are the mass and charge of the revolving electron in the orbit of radius $r$ for hydrogen atom, the total energy of the revolving electron will be:

For an ideal solution of two components $A&B$, which of the following is true?

What happens when an inert gas is added to an equilibrium keeping volume unchanged?

The $\left(\mathrm{S}^{\circ}\right)$ of the following substances are: $\left.\mathrm{CH}_4 \mathrm{~g}\right) 186.2 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ $\mathrm{O}_2$ (g) $205.2 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ $\mathrm{CO}_2(\mathrm{~g}) 213.6 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ $\mathrm{H}_2 \mathrm{O}(\mathrm{g})$ 69.9.JK ${ }^{-1} \mathrm{~mol}^{-1}$ The entropy change $\left(\Delta \mathrm{S}^{\circ}\right)$ for the reaction $\mathrm{CH}_4(\mathrm{~g})+2 \mathrm{O}_2(\mathrm{~g}) \rightarrow \mathrm{CO}_2(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}$ (l) is:

The correct set of four quantum numbers for the valence electrons of rubidium atom $(Z=37)$ is

Assuming that the degree of hydrolysis is small, the $\mathrm{pH}$ of $0.1 \mathrm{M}$ solution of sodium acetate $\left(\mathrm{K}_{\mathrm{a}}=1.0 \times 10^{-5}\right)$ will be:

For complete combustion of ethanol, ${\text{C}}_{2} {\text{H}}_{5} \text{OH} ( \text{l} ) + 3 {\text{O}}_{2} ( \text{g} ) \rightarrow 2 {\text{CO}}_{2} ( \text{g} ) + 3 {\text{H}}_{2} \text{O} ( \text{l} )$, the amount of heat produced as measured in bomb calorimeter, is ${\text{1364.47 kJ mol}}^{-1}$ at $2 5 ℃$. Assuming ideality the Enthalpy of combustion, ${\Delta }_{\text{c}} \text{H}$, for the reaction will be: $( \text{R} = {\text{8.314 kJ mol}}^{-1} )$

Resistance of 0.2 M solution of an electrolyte is $5 0 \Omega$. The specific conductance of the solution is ${\text{1.4 S m}}^{-1}$. The resistance of 0.5 M solution of the same electrolyte is $28 0 \Omega$. The molar conductivity of 0.5 M solution of the electrolyte in ${\text{S m}}^{2} {mol}^{-1}$ is :

Given $$ \mathrm{Fe}^{3+}(\mathrm{aq})+\mathrm{e}^{-} \rightarrow \mathrm{Fe}^{2+}(\mathrm{aq}) ; \mathrm{E}^0=+0.77 \mathrm{~V} $$ $$ \begin{aligned} &\mathrm{Al}^{3+}(\mathrm{aq})+3 \mathrm{e}^{-} \rightarrow \mathrm{Al}(\mathrm{s}) ; \mathrm{E}^0=-1.66 \mathrm{~V} \\ &\mathrm{Br}_2(\mathrm{aq})+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{Br}^{-} ; \mathrm{E}^0=+1.09 \mathrm{~V} \end{aligned} $$ Considering the electrode potentials, which of the following represents the correct order of reducing power?

The wave number of the first emission line in the Balmer series of $\mathrm{H}$-Spectrum is : $(\mathrm{R}=$ Rydberg constant $)$ :

Which one of the following arrangements represents the correct order of the proton affinity of the given species :

Vapour pressure of pure benzene is 119 torr and that of toluene is $37.0$ torr at the same temperature. Mole fraction of toluene in vapour phase which is in equilibrium with a solution of benzene and toluene having a mole fraction of toluene $0.50$, will be :

How many grams of methyl alcohol should be added to $10$ litre tank of water to prevent its freezing at $268 \mathrm{~K}$ ? ( $\mathrm{K}_{\mathrm{f}}$ for water is $1.86 \mathrm{~K} \mathrm{~kg}$ $\left.\mathrm{mol}^{-1}\right)$

Experimentally it was found that a metal oxide has formula ${M}_{0.98}O$. Metal M, is present as ${M}^{2+}$ and ${M}^{3+}$ in its oxide. Fraction of the metal which exists as ${M}^{3+}$ would be:

Which one of the following arrangements represents the correct order of solubilities of sparingly soluble salts $\mathrm{Hg}_2 \mathrm{Cl}_2, \mathrm{Cr}_2\left(\mathrm{SO}_4\right)_3$, $\mathrm{BaSO}_4$ and $\mathrm{CrCl}_3$ respectively?

$10 \mathrm{~mL}$ of $2(\mathrm{M}) \mathrm{~NaOH}$ solution is added to $200 \mathrm{~mL}$ of $0.5$ $\mathrm{(M)}$ of $\mathrm{NaOH}$ solution. What is the final concentration ?

Four successive members of the first row of transition elements are listed below with atomic numbers. Which one of them is expected to have the highest ${\text{E}}_{{\text{M}}^{3+}/{\text{M}}^{2+}}^{o}$ value?

The instantaneous rate of disappearance of $\mathrm{MnO}_4^{-}$ion in the following reaction is $4.56 \times 10^{-3} \mathrm{Ms}^{-1}$ $2 \mathrm{MnO}_4^{-}+10 \mathrm{I}^{-}+16 \mathrm{H}^{+} \rightarrow 2 \mathrm{Mn}^{2+}+5 \mathrm{I}_2+8 \mathrm{H}_2 \mathrm{O}$ The rate of appearance $\mathrm{I}_2$ is :

Given : $$ \begin{gathered} \mathrm{E}_{\frac{1}{2} \mathrm{Cl}_2 / \mathrm{Cl}^{-}}^{\mathrm{o}}=1.36 \mathrm{~V}, \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{\mathrm{o}}=-0.74 \mathrm{~V} \\ \mathrm{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{Cr}^{3+}}^{\mathrm{o}}=1.33 \mathrm{~V}, \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^{\mathrm{o}}=1.51 \mathrm{~V} \end{gathered} $$ The correct order of reducing power of the species $\left(\mathrm{Cr}, \mathrm{Cr}^{3+}, \mathrm{Mn}^{2+}\right.$ and $\left.\mathrm{Cl}^{-}\right)$will be:

Given that: (i) $\Delta_{\mathrm{f}} \mathrm{H}^{\circ}$ of $\mathrm{N}_2 \mathrm{O}$ is $82 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (ii) Bond energies of $\mathrm{N} \equiv \mathrm{N}, \mathrm{N}=\mathrm{N}, \mathrm{O}=\mathrm{O}$ and $\mathrm{N}=\mathrm{O}$ are $946,418,498$ and $607 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively, The resonance energy of $\mathrm{N}_2 \mathrm{O}$ is :

Given Reaction Energy Change $\begin{array}{ll} & \text { (in kJ) } \\ \mathrm{Li}(\mathrm{s}) \rightarrow \mathrm{Li}(\mathrm{g}) & 161 \\ \mathrm{Li}(\mathrm{g}) \rightarrow \mathrm{Li}^{+}(\mathrm{g}) & 520 \\ \frac{1}{2} \mathrm{~F}_2(\mathrm{~g}) \rightarrow \mathrm{F}(\mathrm{g}) & 77 \\ \mathrm{~F}(\mathrm{~g})+\mathrm{e}^{-} \rightarrow \mathrm{F}^{-}(\mathrm{g}) & \begin{array}{l}\text { (Electron gain } \\ \text { enthalpy) }\end{array} \\ \mathrm{Li}^{+}(\mathrm{g})+\mathrm{F}^{-}(\mathrm{g}) \rightarrow \mathrm{LiF}(\mathrm{s}) & -1047 \\ \mathrm{Li}(\mathrm{s})+\frac{1}{2} \mathrm{~F}_2(\mathrm{~g}) \rightarrow \mathrm{LiF}(\mathrm{s}) & -617\end{array}$ Based on data provided, the value of electron gain enthalpy of fluorine would be :

A molecule $M$ associates in a given solvent according to the equation $\mathrm{M} \rightleftharpoons(\mathrm{M})_n$. For a certain concentration of M, the van't Hoff factor was found to be $0.9$ and the fraction of associated molecules was $0.2$. The value of $n$ is:

$\mathrm{NaOH}$ is a strong base. What will be $\mathrm{pH}$ of $5.0 \times 10^{-2} \mathrm{M} \mathrm{NaOH}$ solution ? $(\log 2=0.3)$

The rate constant of a zero order reaction is $2.0 \times$ $10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$. If the concentration of the reactant after 25 seconds is $0.5 \mathrm{M}$. What is the initial concentration?