Physical Chemistry PYQ — Page 71

Identify the correct statement regarding a spontaneous process

Assuming that water vapour is an ideal gas, the internal energy $(\Delta \mathrm{U})$ when $1\mathrm{~mol}$ of water is vapourised at $1 \mathrm{~bar}$ pressure and $100^{\circ} \mathrm{C}$, (Given: Molar enthalpy of vapourization of water at $1 \mathrm{~bar}$ and $373 \mathrm{~K}=41 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\mathrm{R}=8.3 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ ) will be

A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of $290 \mathrm{~mm}$ at $300 \mathrm{~K}$. The vapour pressure of propyl alcohol is $200 \mathrm{~mm}$. If the mole fraction of ethyl alcohol is $0.6$, its vapour pressure (in $\mathrm{mm}$) at the same temperature will be

The energies of activation for forward and reverse reactions for $A_2+B_2 \rightleftharpoons 2 A B$ are $180 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $200 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The presence of catalyst lowers the activation energy of both (forward and reverse) reactions by $100 \mathrm{~kJ} \mathrm{~mol}^{-1}$. The enthalpy change of the reaction $\left(\mathrm{A}_2+\mathrm{B}_2 \longrightarrow 2 \mathrm{AB}\right)$ in the presence of catalyst will be (in $\mathrm{kJ} \mathrm{~mol}^{-1}$ )

The cell, $\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1 \mathrm{M}) \| \mathrm{Cu}^{2+}(1 \mathrm{M})\right| \mathrm{Cu}\left(\mathrm{E}_{\text {cell }}^0=1.10 \mathrm{~V}\right)$, was allowed to be completely discharged at $\mathrm{298~K}$. The relative concentration of $\mathrm{Zn}^{2+}$ to $\mathrm{Cu}^{2+}\left[\frac{\left[\mathrm{Zn}^{2+}\right]}{\left[\mathrm{Cu}^{2+}\right]}\right]$ is

The equivalent conductances of two strong electrolytes at infinite dilution in $\mathrm{H}_2 \mathrm{O}$ (where ions move freely through a solution) at $25^{\circ} \mathrm{C}$ are given below: $\wedge^{\circ} \mathrm{CH}_3 \mathrm{COONa}=91.0 \mathrm{~S} \mathrm{~cm}^2$ /equiv $\wedge_{\mathrm{HCl}}^{\circ}=426.2 \mathrm{~S} \mathrm{~cm^2}$ / equiv What additional information/quantity one needs to calculate $\wedge^{\circ}$ of an aqueous solution of acetic acid?

In a sautrated solution of the sparingly soluble strong electrolyte $\mathrm{AgIO}_3$ (Molecular mass $=283$) the equilibrium which sets in is $\mathrm{AgIO}_{3(\mathrm{s})} \rightleftharpoons \mathrm{Ag}_{(\mathrm{aq})}^{+}+\mathrm{IO}_{3(\mathrm{aq})}^{-}$ If the solubility product constant $\mathrm{K}_{\mathrm{sp}}$ of $\mathrm{AgIO}_3$ at a given temperature is $1.0 \times 10^{-8}$, what is the mass of $\mathrm{AgIO}_3$ contained in $100 \mathrm{~ml}$ of its saturated solution?

Consider the reaction, $2 \mathrm{A}+\mathrm{B} \rightarrow$ Products When concentration of $\mathrm{B}$ alone was doubled, the half-life did not change. When the concentration of $\mathrm{A}$ alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is

The $\mathrm{pKa}$ of a weak acid $(\mathrm{HA})$ is $4.5$. The $\mathrm{pOH}$ of an aqueous buffered solution of $\mathrm{HA}$ in which $50 \%$ of the acid is ionized is

A radioactive element gets spilled over the floor of a room. Its half-life period is $30$ days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room?

The density (in $\mathrm{g} \mathrm{~mL}^{-1}$ ) of a $3.60 \mathrm{~M}$ sulphuric acid solution that is $29 \% ~\mathrm{H}_2 \mathrm{SO}_4$ (Molar mass $=98 \mathrm{~g}$ $\mathrm{mol}^{-1}$ ) by mass will be

Regular use of which of the following fertilizer increases the acidity of soil?

The first and second dissociation constants of an acid $\mathrm{H}_2 \mathrm{A}$ are $1.0 \times 10^{-5}$ and $5.0 \times 10^{-10}$ respectively. The overall dissociation constant of the acid will be

In conversion of lime-stone to lime, $\mathrm{CaCO}_3(\mathrm{~s}) \longrightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_2(\mathrm{~g})$ the vales of $\Delta \mathrm{H}^{\circ}$ and $\Delta \mathrm{S}^{\circ}$ are $+179.1 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $160.2 \mathrm{~J} / \mathrm{K}$ respectively at $298 \mathrm{~K}$ and $1\mathrm{~bar}$. Assuming that $\Delta \mathrm{H}^{\circ}$ do not change with temperature, temperature above which conversion of limestone to lime will be spontaneous is

Which of the following sets of quantum numbers represents the highest energy of an atom?

The molar conductivities $\wedge_{\mathrm{NaOAC}}^{\circ}$ and $\wedge_{\mathrm{HCl}}^{\circ}$ at infinite dilution in water at $25^{\circ} \mathrm{C}$ are $91.0$ and $426.2 \mathrm{~S} \mathrm{~cm}^2 / \mathrm{mol}$ respectively. To calculate $\wedge_{\mathrm{HOAc}}^O$, the additional value required is

Which one of the following sets of ions represents a collection of isoelectronic species?

A reaction was found to be second order with respect to the concentration of carbon monoxide. If the concentration of carbon monoxide is doubled, with everything else kept the same, the rate of reaction will

The enthalpy changes for the following processes are listed below: $\begin{array}{ll}\mathrm{Cl}_2(\mathrm{~g})=2 \mathrm{Cl}(\mathrm{g}), & 242.3 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ \mathrm{I}_2(\mathrm{~g})=2 \mathrm{I}(\mathrm{g}), & 151.0 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ \mathrm{ICl}(\mathrm{g})=\mathrm{I}(\mathrm{g})+\mathrm{Cl}(\mathrm{g}), & 211.3 \mathrm{~kJ} \mathrm{~mol}^{-1} \\ \mathrm{I}_2(\mathrm{~s})=\mathrm{I}_2(\mathrm{~g}), & 62.76 \mathrm{~kJ} \mathrm{~mol}^{-1}\end{array}$ Given that the standard states for iodine and chlorine are $\mathrm{I}_2(\mathrm{~s})$ and $\mathrm{Cl}_2(\mathrm{~g})$, the standard enthalpy of formation for $\mathrm{ICl}(\mathrm{g})$ is

The equilibrium constant for the reaction $$ \mathrm{SO}_3(\mathrm{~g}) \rightleftharpoons \mathrm{SO}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g}) $$ is $\mathrm{K}_{\mathrm{c}}=4.9 \times 10^{-2}$. The value of $\mathrm{K}_{\mathrm{c}}$ for the reaction $$ 2 \mathrm{SO}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{SO}_3(\mathrm{~g}) $$ will be

Given the data at $25^{\circ} \mathrm{C}$, $$ \begin{aligned} & \mathrm{Ag}+\mathrm{I}^{-} \longrightarrow \mathrm{AgI}+\mathrm{e}^{-} ; \mathrm{E}^{\circ}=0.152 \mathrm{~V} \\ & \mathrm{Ag} \longrightarrow \mathrm{Ag}^{+}+\mathrm{e}^{-} ; \quad \mathrm{E}^{\circ}=-0.800 \mathrm{~V} \end{aligned} $$ What is the value of $\log \mathrm{K}_{\mathrm{sp}}$ for $\mathrm{AgI}$ ? $$ \left(2.303 \frac{R T}{F}=0.059 \mathrm{~V}\right) $$

$(\Delta \mathrm{H}-\Delta \mathrm{U})$ for the formation of carbon monoxide (CO) from its elements at $298 \mathrm{~K}$ is $\left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$

How many moles of magnesium phosphate, $\mathrm{Mg}_3\left(\mathrm{PO}_4\right)_2$ will contain $0.25$ mole of oxygen atoms?

Which of the following statements is true?