Physical Chemistry PYQ — Page 40

When light of wavelength $248\mathrm{nm}$ falls on a metal of threshold energy $3.0\mathrm{eV}$, the de-Broglie wavelength of emitted electrons is ________ $\overset{o}{A}$. (Round off to the Nearest Integer). [Use : $\sqrt{3}=1.73,h=6.63\times {10}^{-34}\mathrm{Js};{m}_{e}=9.1\times {10}^{-31}\mathrm{kg};c=3.0\times {10}^{8}{\mathrm{ms}}^{-1};1\mathrm{eV}=1.6\times {10}^{-19}J]$

The oxidation states of $'P'$ in ${H}_{4}{P}_{2}{O}_{7},{H}_{4}{P}_{2}{O}_{5}$ and ${H}_{4}{P}_{2}{O}_{6},$ respectively, are :

For a first order reaction, the ratio of the time for $75%$ completion of a reaction to the time for $50%$ completion is ___________ . (Integer answer)

Electromagnetic radiation of wavelength $663\mathrm{nm}$ is just sufficient to ionise the atom of metal $A$. The ionization energy of metal $A$ in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ is ___. (Rounded-off to the nearest integer) $[h=6.63\times {10}^{-34}\mathrm{Js},c=3.00\times {10}^{8}{\mathrm{ms}}^{-1},{N}_{A}=6.02\times {10}^{23}{\mathrm{mol}}^{-1}]$

In a solvent $50%$ of an acid HA dimerizes and the rest dissociates. The van't Hoff factor of the acid is _____$\times {10}^{-2}$ (Round off to the nearest integer)

A reaction has a half life of $1\mathrm{min}$. The time required for $99.9%$ completion of the reaction is ___ min. (Round off to the Nearest integer) [Use : $\mathrm{ln}2=0.69,\mathrm{ln}10=2.3$]

For the reaction ${A}_{(g)}\rightarrow {B}_{(g)}$, the value of the equilibrium constant at $300K$ and $1\mathrm{atm}$ is equal to $100.0.$ The value of ${\Delta G}^{o}$ for the reaction at $300K$ and $1\mathrm{atm}$ in ${\mathrm{Jmol}}^{-1}$ is $-xR,$ where $x$ is (Rounded off to the nearest integer) $(R=8.31J{\mathrm{mol}}^{-1}{K}^{-1}\mathrm{and}\mathrm{ln}10=2.3)$

$1.46g$ of a biopolymer dissolved in a $100\mathrm{mL}$ water at $300K$ exerted an osmotic pressure of $2.42\times {10}^{-3}\mathrm{bar}$ The molar mass of the biopolymer is $-\times {10}^{4}g$ ${\mathrm{mol}}^{-1}.$ (Round off to the Nearest Integer) [Use: $R=0.083L$ bar ${\mathrm{mol}}^{-1}{K}^{-1}]$

The oxygen dissolved in water exerts a partial pressure of $20\mathrm{kPa}$ in the vapour above water. The molar solubility of oxygen in water is ______ $\times {10}^{-5}\mathrm{mol}{\mathrm{dm}}^{-3}.$ (Round off to the Nearest Integer). [Given : Henry's law constant $={K}_{H}=8.0\times {10}^{4}\mathrm{kPa}$ for ${O}_{2}.$ Density of water with dissolved oxygen$=1.0\mathrm{kg}{\mathrm{dm}}^{-3}$]

The mole fraction of a solute in a $100$ molal aqueous solution ________ $\times {10}^{-2}.$ (Round off to the Nearest Integer). [Given : Atomic masses: $H:1.0u,O:16.0u$]

A $5.0m\mathrm{mol}{\mathrm{dm}}^{-3}$ aqueous solution of $\mathrm{KCl}$ has a conductance of $0.55\mathrm{mS}$ when measured in a cell constant $1.3{\mathrm{cm}}^{-1}$. The molar conductivity of this solution is _______ ${\mathrm{mSm}}^{2}{\mathrm{mol}}^{-1}$. (Round off to the Nearest Integer)

The first order rate constant for the decomposition of ${\mathrm{CaCO}}_{3}$ at $700K$ is $6.36\times {10}^{-3}{s}^{-1}$ and activation energy is $209\mathrm{kJ}{\mathrm{mol}}^{-1}$. Its rate constant (in ${s}^{-1})$ at $600K$ is $x\times {10}^{-6}$. The value of $x$ is (Nearest integer) [Given $R=8.31J{K}^{-1}{\mathrm{mol}}^{-1};\mathrm{log}6.36\times {10}^{-3}=-2.19,{10}^{-4.79}=1.62\times {10}^{-5}]$

Assuming that $\mathrm{Ba}(\mathrm{OH}{)}_{2}$ is completely ionised in aqueous solution under the given conditions the concentration of ${H}_{3}{O}^{+}$ ions in $0.005M$ aqueous solution of $\mathrm{Ba}(\mathrm{OH}{)}_{2}$ at $298K$ is _________ $\times {10}^{-12}\mathrm{mol}{L}^{-1}.$ (Nearest integer)

$83g$ of ethylene glycol dissolved in $625g$ of water. The freezing point of the solution is ..... K. (Nearest integer) [Use : Molal Freezing point depression constant of water $=1.86K\mathrm{kg}{\mathrm{mol}}^{-1}$ Freezing point of water $=273K$ Atomic masses : $C:12.0u,O:16.0u,H:1.0u]$

$\mathrm{Emf}$ of the following cell at $298K$ in $V$ is $x\times {10}^{-2}$ $\mathrm{Zn}|{\mathrm{Zn}}^{2+}(0.1M)\|{\mathrm{Ag}}^{+}(0.01M)|\mathrm{Ag}$ The value of $x$ is ________________ (Rounded off to the nearest integer) $[\mathrm{Given}:{E}_{{\mathrm{Zn}}^{2+}/\mathrm{Zn}}^{\theta }=-0.76V;{E}_{{\mathrm{Ag}}^{+}/\mathrm{Ag}}^{\theta }=+0.80V;\frac{2.303\mathrm{RT}}{F}=0.059]$

For the first order reaction $A\rightarrow 2B,1$ mole of reactant A gives $0.2$ moles of $B$ after $100$ minutes. The half life of the reaction is ...... min. (Round off to the nearest integer). [Use $:\mathrm{ln}2=0.69,\mathrm{ln}10=2.3$ Properties of logarithms $:\mathrm{ln}{x}^{y}=y\mathrm{ln}x$ $\mathrm{ln}(\frac{x}{y})=\mathrm{ln}x-\mathrm{ln}y]$ (Round off to the nearest integer)

Given below are two statements: Statement I : In the titration between strong acid and weak base methyl orange is suitable as an indicator. Statement II : For titration of acetic acid with $\mathrm{NaOH}$ phenolphthalein is not a suitable indicator. In the light of the above statements, choose the most appropriate answer from the options given below:

$1.22g$ of an organic acid is separately dissolved in $100g$ of benzene $({K}_{b}=2.6K\mathrm{kg}{\mathrm{mol}}^{-1})$ and $100g$ of acetone $({K}_{b}=1.7K\mathrm{kg}{\mathrm{mol}}^{-1}).$ The acid is known to dimerize in benzene but remain as a monomer in acetone. The boiling point of the solution in acetone increases by $0.17^{\circ}C.$ The increase in boiling point of solution in benzene in$C\circ$ is $x\times {10}^{-2}.$ The value of $x$ is (Nearest integer) [Atomic mass : $C=12.0,H=1.0,O=16.0$]

For the reaction $A+B\rightleftharpoons 2C$ the value of equilibrium constant is $100$ at $298K$. If the initial concentration of all the three species is $1M$ each, then the equilibrium concentration of $C$ is $x\times {10}^{-1}M$. The value of $x$ is _______. (Nearest integer)

The exact volumes of $1M\mathrm{NaOH}$ solution required to neutralise $50\mathrm{mL}$ of $1M{H}_{3}{\mathrm{PO}}_{3}$ solution and $100\mathrm{mL}$ of $2M{H}_{3}{\mathrm{PO}}_{2}$ solution, respectively, are :

Match List - I with List - II : <table class="pyq-table"><tbody><tr><td></td><td>List - I (Parameter)</td><td></td><td>List - II (Unit)</td></tr><tr><td>(a)</td><td>Cell constant</td><td>(i)</td><td>$S{\mathrm{cm}}^{2}{\mathrm{mol}}^{-1}$</td></tr><tr><td>(b)</td><td>Molar conductivity</td><td>(ii)</td><td>Dimensionless</td></tr><tr><td>(c)</td><td>Conductivity</td><td>(iii)</td><td>${m}^{-1}$</td></tr><tr><td>(d)</td><td>Degree of dissociation of electrolyte</td><td>(iv)</td><td>${\Omega }^{-1}{m}^{-1}$</td></tr></tbody></table>

$200\mathrm{mL}$ of $0.2M\mathrm{HCl}$ is mixed with $300\mathrm{mL}$ of $0.1M\mathrm{NaOH}.$ The molar heat of neutralization of this reaction is $-57.1\mathrm{kJ}.$ The increase in temperature in $C\circ$ of the system on mixing is $x\times {10}^{-2}.$ The value of $x$ is (Nearest integer) [Given: Specific heat of water $=4.18J{g}^{-1}{K}^{-1}$ Density of water$=1.00g{\mathrm{cm}}^{-3}$] (Assume no volume change on mixing)

A certain orbital has $n=4$ and ${m}_{l}=-3.$ The number of radial nodes in this orbital is _______. (Round off to the Nearest Integer).

The value of magnetic quantum number of the outermost electron of ${\mathrm{Zn}}^{+}$ ion is _________ . (Integer answer)