Physical Chemistry PYQ — Page 63

The molecular formula of a commercial resin used for exchanging ions in water softening is ${C}_{8}{H}_{7}S{O}_{3}Na$ $(\mathrm{molecular}\mathrm{weight}=206)$. What would be the maximum uptake of $C{a}^{2+}$ ions by the resin if expressed in $\mathrm{mol}$ per $\mathrm{gm}$?

The vapour pressure of acetone at ${20}^{o}C$ is $185\mathrm{torr}$. When $1.2g$ of a non-volatile substance was dissolved in $100g$ of acetone at ${20}^{o}C$ , its vapour pressure was $183\mathrm{torr}$. The molar mass $(g mo{l}^{-1})$ of the substance is:

Determination of the molar mass of acetic acid in benzene using freezing point depression is affected by:

The following reaction is performed at $298K$. $2NO(g)+{O}_{2}(g)\rightleftharpoons 2N{O}_{2}(g)$ The standard free energy of the formation of $NO(g)$ is $86.6\mathrm{kJ}{\mathrm{mol}}^{-1}$ at $298K$. What is the standard free energy of the formation of $N{O}_{2}(g)$ at $298K$? $({K}_{P}=1.6\times {10}^{12})$

At $298K$, the standard reduction potentials are $1.51V$ for ${MnO}_{4}^{-} | M{n}^{2+}$, $1.36V$ for $C{l}_{2}|C{l}^{-}$, $1.07V$ for $B{r}_{2}|B{r}^{-}$, $0.54V$ for ${I}_{2}|{I}^{-}$. At $\mathrm{pH}=3$, permanganate is expected to oxidize: $(\frac{RT}{F}=0.059)$

Gaseous ${N}_{2}{O}_{4}$ dissociates into gaseous $N{O}_{2}$ according to the reaction ${N}_{2}{O}_{4}(g)\rightleftharpoons 2N{O}_{2}(g)$ At $300K$ and $1\mathrm{atm}$ pressure, the degree of dissociation of ${N}_{2}{O}_{4}$ is $0.2$. If one mole of ${N}_{2}{O}_{4}$ gas is contained in a vessel, then the density of the equilibrium mixture is$:$

The increase of pressure on $ice \rightleftharpoons water$ system at constant temperature will lead to:

The reaction $2{N}_{2}{O}_{5}(g)\rightarrow 4N{O}_{2}(g)+{O}_{2}(g)$ follows first order kinetics. The pressure of a vessel containing only ${N}_{2}{O}_{5}$ was found to increase from 50 mm Hg to 87.5 mm Hg in 30 min. The pressure exerted by the gases after 60 min. Will be (Assume temperature remains constant) :

If the principal quantum number $\text{n}=6,$ the correct sequence of filling of electrons will be:

A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu)

The half-life period of a first-order reaction is $15\text{minutes}$. The amount of substance left after one hour will be

Consider the following equilibrium $$ \mathrm{AgCl} \downarrow+2 \mathrm{NH}_3 \rightleftharpoons\left[\mathrm{Ag}\left(\mathrm{NH}_3 2_2\right]^{+}+\mathrm{Cl}^{-}\right. $$ White precipitate of $\mathrm{AgCl}$ appears on adding which of the following?

The metal that cannot be obtained by the electrolysis of an aqueous solution of its salt is

The amount of oxygen in $3.6$ moles of water is:

For the decomposition of the compound, represented as ${\text{NH}}_{2} {\text{COONH}}_{4} ( \text{s} ) \rightleftharpoons 2 {\text{NH}}_{3} ( \text{g} ) + {\text{CO}}_{2} ( \text{g} )$ the ${K}_{p}=2.9\times {10}^{-5}{atm}^{3}$. If the reaction is started with 1 mole of the compound, the total pressure at equilibrium would be :

The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecules is:

The standard enthalpy of formation of${\mathrm{NH}}_{3}$ is $-46.0\mathrm{kJ}/\mathrm{mol}$. If bond enthalpy of ${H}_{2}$ is $-436\mathrm{kJ}/\mathrm{mol}$ and that of ${N}_{2}$ is $-712\mathrm{kJ}/\mathrm{mol}$ , the average bond enthalpy of $N-H$ bond in ${\mathrm{NH}}_{3}$ is :

In the reaction of formation of sulphur trioxide by contact process $2 \mathrm{SO}_2+\mathrm{O}_2 \rightleftharpoons 2 \mathrm{SO}_3$ the rate of reaction was measured as $\frac{\mathrm{d}\left[\mathrm{O}_2\right]}{\mathrm{dt}}=-2.5 \times 10^{-4} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$. The rate of reaction is terms of $\left[\mathrm{SO}_2\right]$ in $\mathrm{mol} \mathrm{L}^{-1} \mathrm{~s}^{-1}$ will be:

The ionization energy of gaseous $\mathrm{Na}$ atoms is $495.5\mathrm{kJ}{\mathrm{mol}}^{-1}$. The lowest possible frequency of light that ionizes a sodium atom is $(\text{h}=\text{6.626}\times 1{0}^{-34}Js,{N}_{\text{A}}=\text{6.022}\times 1{0}^{23}{mol}^{-1})$

The energy of an electron in first Bohr's orbit of H atom is $-13.6 \text{eV}\text{.}$ The energy value of electron in the first excited state of ${ \text{Li}}^{ \text{2+}}$ is :

Dissolving 120 g of a compound of (mol. wt. 60) in 1000 g of water gave a solution of density 1.12 g/mL. The molarity of the solution is :

Based on the equation: $$ \Delta \mathrm{E}=-2.0 \times 10^{-18} \mathrm{~J}\left(\frac{1}{\mathrm{n}_2^2}-\frac{1}{\mathrm{n}_1^2}\right) $$ the wavelength of the light that must be absorbed to excite hydrogen electron from level $n=1$ to level $\mathrm{n}=2$ will be: $\left(\mathrm{h}=6.625 \times 10^{-34} \mathrm{Js}, \mathrm{C}=3 \times 10^8 \mathrm{~ms}^{-1}\right)$

The rate coefficient $(k)$ for a particular reactions is $1.3 \times 10^{-4} \mathrm{M}^{-1} \mathrm{~s}^{-1}$ at $100^{\circ} \mathrm{C}$, and $1.3 \times 10^{-3}$ $\mathrm{M}^{-1} \mathrm{~s}^{-1}$ at $150^{\circ} \mathrm{C}$. What is the energy of activation $\left(\mathrm{E}_{\mathrm{A}}\right)$ (in $\left.\mathrm{kJ}\right)$ for this reaction? $(\mathrm{R}=$ molar gas constant $=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ )

For the reaction, $\text{3A} + \text{2B} \rightarrow \text{C} + \text{D}$, the differential rate law can be written as :