Physical Chemistry PYQ — Page 73

Which of the following statements in relation to the hydrogen atom is correct?

The highest electrical conductivity of the following aqueous solutions is of

Calomel $\left(\mathrm{Hg}_2 \mathrm{Cl}_2\right)$ on reaction with ammonium hydroxide gives

Consider the reaction: $\mathrm{N}_2+3 \mathrm{H}_2 \longrightarrow 2 \mathrm{NH}_3$ carried out at constant temperature and pressure. If $\Delta \mathrm{H}$ and $\Delta \mathrm{U}$ are the enthalpy and internal energy changes for the reaction, which of the following expressions is true?

Consider an endothermic reaction, $X \longrightarrow Y$ with the activation energies $E_b$ and $E_f$ for the backward and forward reactions, respectively. In general

For the reaction $$ \begin{aligned} & 2 \mathrm{NO}_{2(\mathrm{~g})} \rightleftharpoons 2 \mathrm{NO}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \text {, } \\ & \left(\mathrm{K}_{\mathrm{c}}=1.8 \times 10^{-6} \text {at } 184 \mathrm{C}\right) \\ & (\mathrm{R}=0.0831 \mathrm{~kJ} /(\mathrm{mol} . \mathrm{K}) \end{aligned} $$ When $\mathrm{K}_{\mathrm{p}}$ and $\mathrm{K}_{\mathrm{c}}$ are compared at $184^{\circ} \mathrm{C}$, it is found that

What is the conjugate base of $\mathrm{OH}^{-} ?$

Equimolar solutions in the same solvent have

If $\alpha$ is the degree of dissociation of $\mathrm{Na}_2 \mathrm{SO}_4$, the vant Hoff's factor (i) used for calculating the molecular mass is

In a multi – electron atom, which of the following orbitals described by the three quantum numbers will have the same energy in the absence of magnetic acid and electric fields? (a) $n=1, l=0, m=0$ (b) $n=2, l=0, m=0$ (c) $n=2, l=1, m=1$ (d) $n=3, l=2, m=1$ (e) $n=3, l=2, m=0$

 Calculate $\wedge_{H O A c}^{\infty}$ Using appropriate molar conductances of the electrolytes listed above at infinite dilution in $\mathrm{H}_2 \mathrm{O}$ at $25^{\circ} \mathrm{C}$

An amount of solid $\mathrm{NH}_4 \mathrm{HS}$ is placed in a flask already containing ammonia gas at a certain temperature and $0.50 \mathrm{~atm}$. Pressure. Ammonium hydrogen sulphide decomposes to yield $\mathrm{NH}_3$ and $\mathrm{H}_2 \mathrm{~S}$ gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to $0.84 \mathrm{~atm}$. The equilibrium constant for $\mathrm{NH}_4 \mathrm{HS}$ decomposition at this temperature is

The enthalpies of combustion of carbon and carbon monoxide are $-393.5$ and $-283 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The enthalpy of formation of carbon monoxide per mole is

In a cell that utilises the reaction $\mathrm{Zn}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})$ addition of $\mathrm{H}_2 \mathrm{SO}_4$ to cathode compartment, will

The $\mathrm{E}_{\mathrm{M}^{+3} / \mathrm{M}^{2+}}^{\circ}$ values for $\mathrm{Cr}, \mathrm{Mn}, \mathrm{Fe}$ and Co are $-0.41,+1.57,+0.77$ and $+1.97 \mathrm{~V}$ respectively. For which one of these metals the change in oxidation state form $+2$ to $+3$ is easiest?

Consider the following $\mathrm{E}^{\circ}$ values $$ \begin{aligned} & \mathrm{E}_{\mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}}^{\circ}=0.77 \mathrm{~V} \\ & \mathrm{E}_{\mathrm{Sn}^{2+} / \mathrm{Sn}}^{\circ}=-0.14 \mathrm{~V} \end{aligned} $$ Under standard conditions the potential for the reaction $\mathrm{Sn}(\mathrm{s})+2 \mathrm{Fe}^{3+}(\mathrm{aq}) \longrightarrow 2 \mathrm{Fe}^{2+}(\mathrm{aq})+\mathrm{Sn}^{2+}(\mathrm{aq})$ is

Consider the ground state of $\mathrm{Cr}$ atom $(Z=24)$. The number of electrons with the azimuthal quantum numbers $\mathrm{I}=1$ and 2 are respectively

Which of the following sets of quantum numbers is correct for an electron in $4 \mathrm{f}$ orbital?

The standard e.m.f of a cell, involving one electron change is found to be $0.591 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$. The equilibrium constant of the reaction is $\left(\mathrm{F}=96,500 \mathrm{C} \mathrm{mol}^{-1}: \mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)$

The wavelength of the radiation emitted, when in hydrogen atom electron falls from infinity to stationary state 1 , would be (Rydberg constant $\left.=1.097 \times 10^7 \mathrm{~m}^{-1}\right)$

To neutralize completely $20 \mathrm{~mL}$ of $0.1 \mathrm{M}$ aqueous solution of phosphorous acid $\left(\mathrm{H}_3 \mathrm{PO}_3\right)$, the volume of $0.1 \mathrm{M}$ aqueous $\mathrm{KOH}$ solution required is

The equilibrium constant for the reaction $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ at temperature $\mathrm{T}$ is $4 \times 10^{-4}$. The value of $\mathrm{Kc}$ for the reaction $\mathrm{NO}(\mathrm{g}) \rightleftharpoons \frac{1}{2} \mathrm{~N}_2(\mathrm{~g})+\frac{1}{2} \mathrm{O}_2(\mathrm{~g})$ at the same temperature is

In hydrogen - oxygen fuel cell, combustion of hydrogen occurs to

In first order reaction, the concentration of the reactant decreases from $0.8 \mathrm{M}$ to $0.4 \mathrm{M}$ in 15 minutes. The time taken for the concentration to change from $0.1 \mathrm{M}$ to $0.025 \mathrm{M}$ is