Physical Chemistry PYQ — Page 49

The region in the electromagnetic spectrum where the Balmer series lines appear is:

The value of ${K}_{c}\mathrm{us}64\mathrm{at}800K$ for the reaction ${N}_{2}(g)+3{H}_{2}(g)\rightarrow 2{\mathrm{NH}}_{3}(g)$ The value of ${K}_{c}$ for the following reaction is : ${\mathrm{NH}}_{3}(g)\rightarrow \frac{1}{2}{N}_{2}(g)+\frac{3}{2}{H}_{2}(g)$

A solution of two components containing ${n}_{1}$ moles of the ${1}^{\text{st }}$ component and ${n}_{2}$moles of the ${2}^{\text{nd }}$ component is prepared. ${M}_{1}$ and ${M}_{2}$ are the molecular weights of component 1 and 2 respectively. If $d$ is the density of the solution in ${\mathrm{gmI}}^{-1},{C}_{2}$ is the molarity and ${x}_{2}$ is the mole fraction of the ${2}^{\text{nd }}$ component, then ${C}_{2}$ can be expressed as :

For the Balmer series, in the spectrum of $H$ atom, $\overset{-}{v}={R}_{H}{\frac{1}{{n}_{1}^{2}}-\frac{1}{{n}_{2}^{2}}},$ the correct statements among $(I)$ to $(IV)$ are, $(I)$ As wavelength decreases, the lines in the series converge. $(II)$ The integer ${n}_{1}$ is equal to $2$/ $(III)$ The lines of the longest wavelength correspond to ${n}_{2}=3$. $(IV)$ The ionization energy of hydrogen can be calculated from the wave number of these lines.

 ${E}_{{\mathrm{Cu}}^{2+}|\mathrm{Cu}}^{0}=+0.34V$ ${E}_{{\mathrm{Zn}}^{2+}|\mathrm{Zn}}^{0}=-0.76V$ Identify the incorrect statement from the options below for the above cell:

The magnitude of work done by a gas that undergoes a reversible expansion along the path $ABC$ shown in the figure is _________. 

The variation of equilibrium constant with temperature is given below : $\begin{matrix}\mathrm{Temperature} & \mathrm{EquilibriumConstant} \\ {T}_{1}=25^{\circ}C & {K}_{1}=10 \\ {T}_{2}=100^{\circ}C & {K}_{2}=100\end{matrix}$ The values of $\Delta H^{\circ},\Delta G^{\circ}$ at ${T}_{1}$ and $\Delta G^{\circ}$ at ${T}_{2}$ (in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ ) respectively, are close to [use $R=8.314{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1}$]

A sample of milk splits after $60min$ . at $300K$ and after $40min$ . at $400K$ when the population of Iactobacillus acidophilus in it doubles. The activation energy (in $\mathrm{kJ}/\mathrm{mol}$ ) for this process is closest to ______________. (Given, $R=8.3Jmo{l}^{-1}{K}^{-1},ln(\frac{2}{3})=0.4,{e}^{-3}=4.0$ )

An acidic solution of dichromate is electrolyzed for 8 minutes using 2 A current. As per the following equation ${\mathrm{Cr}}_{2}{O}_{7}^{2}+14{H}^{+}+6{e}^{-}\rightarrow 2{\mathrm{Cr}}^{3+}+7{H}_{2}O$ The amount of ${\mathrm{Cr}}^{3+}$. obtained was $0.104g$. The efficiency of the process $(\mathrm{in}%)$ is (Take : $F=960000C$, At. mass of chromium $=52$)

The volume strength of $8.9{\mathrm{MH}}_{2}{O}_{2}$ solution calculated at $273K$ and 1 atm is $........(R=0.0821L\mathrm{atm}{K}^{-1}{\mathrm{mol}}^{-1})$ (rounded off to the nearest integer)

Oxidation number of potassium in ${K}_{2}O,{K}_{2}{O}_{2}$ and $K{O}_{2},$ respectively, is:

The number of subshells associated with $n=4$ and $m=-2$ quantum numbers is:

Consider the following reaction: ${N}_{2}{O}_{4}(g)=2{\mathrm{NO}}_{2}(g):\Delta {H}^{0}=+58k$ For each of the following cases $(a,b)$, the direction in which the equilibrium shifts is: (a) Temperature is decreased. (b) Pressure is increased by adding ${N}_{2}$ at constant T.

The number of orbitals associated with quantum numbers $n=5,{m}_{s}=+\frac{1}{2}$ is:

A graph of vapour pressure and temperature for three different liquids $X,Y$ and $Z$ is shown below:  The following inferences are made: $(A)X$ has higher intermolecular interactions compared to $Y.$ $(B)X$ has lower intermolecular interactions compared to $Y.$ $(C)Z$ has lower intermolecular interactions compared to $Y.$ The correct inferences is/are:

The equation that is incorrect is:

Amongst the following statements, that which was not proposed by Dalton was :

The work function of sodium metal is $4.41\times {10}^{-19}J.$ If photons of wavelength $300\mathrm{nm}$ are incident on the metal, the kinetics energy of the ejected electrons will be $(h=6.63\times {10}^{-34}Js;c=3\times {10}^{8}m{s}^{-1})$__________$\times {10}^{-21}J$

The Gibbs energy change (in $J$) for the given reaction at $[{\mathrm{Cu}}^{2+}]=[{\mathrm{Sn}}^{2}+]=1\text{ M}$ and $298K$ is : $\mathrm{Cu}(s)+{\mathrm{Sn}}^{2+}(\mathrm{aq}.)\rightarrow {\mathrm{Cu}}^{2+}(\mathrm{aq}.)+\mathrm{Sn}(s)$; $({E}_{{\mathrm{Sn}}^{2+}|\mathrm{Sn}}^{0}=-0.16 V, {E}_{{\mathrm{Cu}}^{2+}|\mathrm{Cu}}^{0}=0.34 V,$Take $F=96500 C {\mathrm{mol}}^{-1})$

The photoelectric current from Na (work function, ${w}_{0}=2.3\mathrm{eV}$) is stopped by the output voltage of the cell $\mathrm{Pt}(s)\|{H}_{2}(g,1\mathrm{bar})|\mathrm{HCl}(\mathrm{aq}\cdot ,\mathrm{pH}=1)|\mathrm{AgCl}(s)\mid \mathrm{Ag}(s)$ the $pH$ of aq. $\mathrm{HCl}$ required to stop the photoelectric current from $K({w}_{0}=2.25\mathrm{eV})$, all other conditions remaining the same, is $\ldots \ldots \ldots .\times {10}^{-2}$ (to the nearest integer). Given $2.303\frac{\mathrm{RT}}{F}=0.06V;{E}_{\mathrm{AgCl}/\mathrm{Ag}/Cl}^{0}=0.22V$

For an electrochemical cell $\mathrm{Sn}(s)|{\mathrm{Sn}}^{2}+(\mathrm{aq}, 1M)||{\mathrm{Pb}}^{2+}(\mathrm{aq}, 1M)|\mathrm{Pb}(s)$ the ratio $\frac{[{\mathrm{Sn}}^{2+}]}{[{\mathrm{Pb}}^{2+}]}$ when this cell attains equilibrium is _______ (Given: ${E}_{{\mathrm{Sn}}^{2+}|\mathrm{Sn}}^{0}=-0.14 V,{E}_{{\mathrm{Pb}}^{2+}|\mathrm{Pb}}^{0}=-0.13 V, \frac{2.303\mathrm{RT}}{F}=0.06$)

Potassium chlorate is prepared by the electrolysis of $\mathrm{KCl}$ in basic solution $6{\mathrm{OH}}^{-}+{\mathrm{Cl}}^{-}\rightarrow {\mathrm{ClO}}_{3}^{-}+3{H}_{2}O+6{e}^{-}$ . If only $60%$ of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce$10g$ of ${\mathrm{KClO}}_{3}$ using a current of $2A$ is $\ldots \ldots ..$ (Given :$F=96,500C$$\mathrm{mol}$; molar mass of ${\mathrm{KClO}}_{3}=122g{\mathrm{mol}}^{-1}$)

Consider the following reactions $A\rightarrow P1;B\rightarrow P2;C\rightarrow P3;D\rightarrow P4$ The order of the above reactions are $a,b,c\mathrm{and}d,$respectively. The following graph is obtained when log[rate] vs.log[conc.] are plotted:  Among the following, the correct sequence for the order of the reactions is :

The rate of a certain biochemical reaction at physiological temperature $(T)$ occurs ${10}^{6}$ times faster with enzyme than without. The change in the activation energy upon adding enzyme is: