Physical Chemistry PYQ — Page 46

The stepwise formation of ${[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{4}]}^{2+}$ is given below: ${\mathrm{Cu}}^{2+}+{\mathrm{NH}}_{3}\overset{{K}_{1}}{\rightleftharpoons }{[\mathrm{Cu}({\mathrm{NH}}_{3})]}^{2+}$ ${[\mathrm{Cu}({\mathrm{NH}}_{3})]}^{2+}+{\mathrm{NH}}_{3}\overset{{K}_{2}}{\rightleftharpoons }{[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{2}]}^{2+}$ ${[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{2}]}^{2+}+{\mathrm{NH}}_{3}\overset{{K}_{3}}{\rightleftharpoons }{[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{3}]}^{2+}$ ${[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{3}]}^{2+}+{\mathrm{NH}}_{3}\overset{{K}_{4}}{\rightleftharpoons }{[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{4}]}^{2+}$ The value of stability constants ${K}_{1},{K}_{2},{K}_{3}$ and ${K}_{4}$ are ${10}^{4},1.58\times {10}^{3},5\times {10}^{2}$ and ${10}^{2}$ respectively. The overall equilibrium constants for dissociation of ${[\mathrm{Cu}{({\mathrm{NH}}_{3})}_{4}]}^{2+}$ is $x\times {10}^{-12}.$ The value of $x$ is _____ (Rounded off to the nearest integer)

${\mathrm{PCl}}_{5}(g)\rightarrow {\mathrm{PCl}}_{3}(g)+{\mathrm{Cl}}_{2}(g)$ In the above first order reaction the concentration of ${\mathrm{PCl}}_{5}$ reduces from initial concentration $50\mathrm{mol}{L}^{-1}$ to $10\mathrm{mol}{L}^{-1}$ in $120$ minutes at $300K.$ The rate constant for the reaction at $300K$ is $x\times {10}^{-2}{\mathrm{min}}^{-1}.$ The value of $x$ is __________. [Given $\mathrm{log}5=0.6989$]

The reaction rate for the reaction ${[{\mathrm{PtCl}}_{4}]}^{2-}+{H}_{2}O\rightleftharpoons {[\mathrm{Pt}({H}_{2}O){\mathrm{Cl}}_{3}]}^{-}+{\mathrm{Cl}}^{-}$ was measured as a function of concentrations of different species. It was observed that $\frac{-d[{[{\mathrm{PtCl}}_{4}]}^{2-}]}{\mathrm{dt}}=4.8\times {10}^{-5}[{[{\mathrm{PtCl}}_{4}]}^{2-}]-2.4\times {10}^{-3}[{[\mathrm{Pt}({H}_{2}O){\mathrm{Cl}}_{3}]}^{-}][{\mathrm{Cl}}^{-}]$ where square brackets are used to denote molar concentrations. The equilibrium constant ${K}_{c}=X$(Nearest integer) Value of $\frac{1}{X}is$ (question is modified.)

${\mathrm{Cu}}^{2+}$ salt reacts with potassium iodide to give

The plots of radial distribution functions for various orbitals of hydrogen atom against ' $r'$ are given below.The correct plot for $3s$ orbital is :

An inorganic Compound $'X'$ on treatment with concentrated ${H}_{2}{\mathrm{SO}}_{4}$ produces brown fumes and gives dark brown ring with ${\mathrm{FeSO}}_{4}$ in presence of concentrated ${H}_{2}{\mathrm{SO}}_{4}$. Also Compound $'X'$ gives precipitate $'Y'$, when its solution in dilute $\mathrm{HCl}$ is treated with ${H}_{2}S$ gas. The precipitate $'Y'$ on treatment with concentrated ${\mathrm{HNO}}_{3}$ followed by excess of ${\mathrm{NH}}_{4}\mathrm{OH}$ further gives deep blue coloured solution, Compound $'X'$ is:

Consider the following reaction ${\mathrm{MnO}}_{4}^{-}+8{H}^{+}+5{e}^{-}\rightarrow {\mathrm{Mn}}^{+2}+4{H}_{2}O,E^{\circ}=1.51V$ The quantity of electricity required in Faraday to reduce five moles of ${\mathrm{MnO}}_{4}^{-}$ is

$250\mathrm{mL}$ of $0.5M\mathrm{NaOH}$ was added to $500\mathrm{mL}$ of $1M$ $\mathrm{HCl}$. The number of unreacted $\mathrm{HCl}$ molecules in the solution after the complete reaction is p$\times {10}^{21}$. Find out p (Nearest integer) $({N}_{A}=6.022\times {10}^{23})$

At $363K$, the vapour pressure of $A$ is $21\mathrm{kPa}$ and that of $B$ is $18\mathrm{kPa}$. One mole of $A$ and $2$ moles of $B$ are mixed. Assuming that this solution is ideal, the vapour pressure of the mixture is___________ $\mathrm{kPa}$. $($Round of to the Nearest Integer$)$.

Which one of the following $0.06M$ aqueous solutions has lowest freezing point ?

For a reaction of order $n,$ the unit of the rate constant is :

The $\mathrm{pH}$ of ammonium phosphate solution, if ${\mathrm{pk}}_{a}$ of phosphoric acid and ${\mathrm{pk}}_{b}$ of ammonium hydroxide are $5.23$ and $4.75$ respectively, is

Methylation of $10g$ of benzene gave $9.2g$ of toluene. Calculate the percentage yield of toluene (Nearest integer)

The number of $f$ electrons in the ground state electronic configuration of $\mathrm{Np}(Z=93)$ is ______ .(Integer answer)

At $20^{\circ}C$, the vapour pressure of benzene is $70$ torr and that of methyl benzene is $20$ torr. The mole fraction of benzene in the vapour phase at $20^{\circ}C$ above an equimolar mixture of benzene and methyl benzene is $__\times {10}^{-2}.$ (Nearest integer)

If the conductivity of mercury at $0^{\circ}C$ is $1.07\times {10}^{6}S{m}^{-1}$ and the resistance of a cell containing mercury is $0.243\Omega ,$ then the cell constant of the cell is $x\times {10}^{4}{m}^{-1}.$ The value of $x$ is ______ . (Nearest integer)

The spin only magnetic moments (in BM) for free ${\mathrm{Ti}}^{3+},{V}^{2+}$ and ${\mathrm{Sc}}^{3+}$ ions respectively are (At.No. $\mathrm{Sc}$ : $21,\mathrm{Ti}:22,V:23$ )

For the reaction $A\rightarrow B,$ the rate constant $k$ (in ${s}^{-1}$) is given by ${\mathrm{log}}_{10}k=20.35-\frac{(2.47\times {10}^{3})}{T}$ The energy of activation in $\mathrm{kJ}{\mathrm{mol}}^{-1}$ is ________ . (Nearest integer) [Given : $R=8.314J{K}^{-1}{\mathrm{mol}}^{-1}$]

A certain orbital has no angular nodes and two radial nodes. The orbital is:

For a chemical reaction $A+B=C+D$ $({\Delta }_{r}{H}^{\Theta }=80\mathrm{kJ}{\mathrm{mol}}^{-1})$ the entropy change ${\Delta }_{r}{S}^{\Theta }$ depends on the temperature $T$ (in $K$) as ${\Delta }_{r}{S}^{\Theta }=2T({\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1})$. Minimum temperature at which it will become spontaneous is $K$. (Integer)

A $50$ watt bulb emits monochromatic red light of wavelength of $795\mathrm{nm}$. The number of photons emitted per second by the bulb is $x\times {10}^{20}.$ The value of $x$ is _____ . (Nearest integer) $\text{ [Given : }h=6.63\times {10}^{-34}\mathrm{Js}\text{ and}c=3.0\times {10}^{8}{\mathrm{ms}}^{-1}]$

${A}_{3}{B}_{2}$ is a sparingly soluble salt of molar mass $M(g{\mathrm{mol}}^{-1})$ and solubility $xg{L}^{-1}.$ The solubility product satisfies ${K}_{\mathrm{sp}}=a{(\frac{x}{M})}^{5}.$ The value of $a$ is __________ . (Integer answer)

When $35\mathrm{mL}$ of $0.15M$ lead nitrate solution is mixed with $20\mathrm{mL}$ of $0.12M$ chromic sulphate solution, ____________$\times {10}^{-5}$ moles of lead sulphate precipitate out. (Round off to the Nearest Integer).

$1$ molal aqueous solution of an electrolyte ${A}_{2}{B}_{3}$ is $60%$ ionised. The boiling point of the solution at $1\mathrm{atm}$ is _____ $K$. (Rounded-off to the nearest integer) [Given ${K}_{b}$ for $({H}_{2}O)=0.52K\mathrm{kg}{\mathrm{mol}}^{-1}$]