Physical Chemistry PYQ — Page 22

Consider the dissociation of the weak acid \(\mathrm{HX}\) as given below \(\mathrm{HX}(\mathrm{aq}) \rightleftharpoons \mathrm{H}^{+}(\mathrm{aq})+\mathrm{X}^{-}(\mathrm{aq}), \mathrm{Ka}=1.2 \times 10^{-5}\) \(\left[\mathrm{K}_{\mathrm{a}}\right.\) : dissociation constant \(]\) The osmotic pressure of \(0.03 \mathrm{M}\) aqueous solution of \(\mathrm{HX}\) at \(300 \mathrm{~K}\) is _______ \(\times 10^{-2}\) bar (nearest integer). [Given : \(\mathrm{R}=0.083 \mathrm{~L} \mathrm{bar} \mathrm{mol}^{-1} \mathrm{~K}^{-1}\)]

${\mathrm{KMnO}}_{4}$ decomposes on heating at $513K$ to form ${O}_{2}$ along with

Standard enthalpy of vapourisation for ${\mathrm{CCl}}_{4}$ is $30.5\mathrm{kJ}{\mathrm{mol}}^{-1}$. Heat required for vapourisation of $284g$ of ${\mathrm{CCl}}_{4}$ at constant temperature is __________ $\mathrm{kJ}$. (Given molar mass in ${\mathrm{gmol}}^{-1};C=12,\mathrm{Cl}=35.5$) Round off your answer to the nearest integer.

Only \(2 \mathrm{~mL}\) of \(\mathrm{KMnO}_4\) solution of unknown molarity is required to reach the end point of a titration of \(20 \mathrm{~mL}\) of oxalic acid \((2 \mathrm{M})\) in acidic medium. The molarity of \(\mathrm{KMnO}_4\) solution should be \(\qquad\) M.

The hydrogen electrode is dipped in a solution of $\mathrm{pH}=3$ at $25^{\circ}C$. The potential of the electrode will be $-$______$\times {10}^{-2}V$. $(\frac{2.303\mathrm{RT}}{F}=0.059V)$ Round off the answer to the nearest integer.

If a substance $'A'$ dissolves in solution of a mixture of ' $B$' and ' $C$ ' with their respective number of moles as ${n}_{A},{n}_{B}$ and ${n}_{C}$, mole fraction of $C$ in the solution is:

Based on Heisenberg's uncertainty principle, the uncertainty in the velocity of the electron to be found within an atomic nucleus of diameter \(10^{-15} \mathrm{~m}\) is ________. \(10^9 \mathrm{~ms}^{-1}\) (nearest integer) [Given : mass of electron \(=9.1 \times 10^{-31} \mathrm{~kg}\), Plank's constant \((h)=6.626 \times 10^{-34} \mathrm{Js}\)] (Value of \(\pi=3.14\))

The amount of electricity in Coulomb required for the oxidation of $1\mathrm{mol}$ of ${H}_{2}O$ to ${O}_{2}$ is ______ $\times {10}^{5}C.$

Consider the following reaction: $3{\mathrm{PbCl}}_{2}+2{({\mathrm{NH}}_{4})}_{3}{\mathrm{PO}}_{4}\rightarrow {\mathrm{Pb}}_{3}{({\mathrm{PO}}_{4})}_{2}+6{\mathrm{NH}}_{4}\mathrm{Cl}$ If $72\mathrm{mmol}{\mathrm{PbCl}}_{2}$ is mixed with $50\mathrm{mmol}$ of ${({\mathrm{NH}}_{4})}_{3}{\mathrm{PO}}_{4},$ then amount of ${\mathrm{Pb}}_{3}{({\mathrm{PO}}_{4})}_{2}$ formed in $\mathrm{mmol}$. (nearest integer)

During Kinetic study of reaction \(2 A+B \rightarrow C+D\), the following results were obtained : \(\begin{array}{llll} & \text { A [M] } & \text { B [M] } & \text { initial rate of formation of D } \\ \text { I } & 0.1 & 0.1 & 6.0 \times 10^{-3} \\ \text { II } & 0.3 & 0.2 & 7.20 \times 10^{-2} \\ \text { III } & 0.3 & 0.4 & 2.88 \times 10^{-1} \\ \text { IV } & 0.4 & 0.1 & 2.40 \times 10^{-2} \\ \end{array}\) Based on above data, overall order of the reaction is ______

Number of spectral lines obtained in ${\mathrm{He}}^{+}$ spectra, when an electron makes transition from fifth excited state to first excited state will be

The molarity of pure water is approximately

We have three aqueous solutions of $\mathrm{NaCl}$ labelled as $‘A’,‘B’$ and $‘C’$ with concentration $0.1M,0.01M$ and $0.001M,$ respectively. The value of van $t’$ Haft factor $(i)$ for these solutions will be in the order.

The reaction; \(\frac{1}{2} \mathrm{H}_{2(\mathrm{~g})}+\mathrm{AgCl}_{(\mathrm{s})} \rightarrow \mathrm{H}_{(\mathrm{aq})}^{+}+\mathrm{Cl}_{(\mathrm{aq})}^{-}+\mathrm{Ag}_{(\mathrm{s})}\) occurs in which of the following galvanic cell :

Choose the Incorrect Statement about Dalton's Atomic Theory

Which out of the following is a correct equation to show change in molar conductivity with respect to concentration for a weak electrolyte, if the symbols carry their usual meaning :

A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ________ (Integer answer) (Given : Molar mass in \(\mathrm{g} \mathrm{mol}^{-1}\) Ethyl alcohol : 46 water: 18)

The maximum number of orbitals which can be identified with \(\mathrm{n}=4\) and \(m_l=0\) is ______

For hydrogen atom, energy of an electron in first excited state is \(-3.4 \mathrm{eV}, \mathrm{K} . \mathrm{E}\). of the same electron of hydrogen atom is \(x \mathrm{eV}\). Value of \(x\) is ______ \(\times 10^{-1} \mathrm{eV}\). (Nearest integer)

Given below are two statements: Statement-I: The orbitals having same energy are called as degenerate orbitals. Statement-II: In hydrogen atom, $3p$ and $3d$ orbitals are not degenerate orbitals. In the light of the above statements, choose the most appropriate answer from the options given

The number of radial node/s for $3p$ orbital is:

Given below are two statements : Statement I: ${S}_{8}$ solid undergoes disproportionation reaction under alkaline conditions to form ${S}^{2-}$ and ${S}_{2}{O}_{3}^{2-}$ Statement II: ${\mathrm{ClO}}_{4}^{-}$ can undergo disproportionation reaction under acidic condition. In the light of the above statements, choose the most appropriate answer from the options given below:

Wavenumber for a radiation having \(5800 Ã…\) wavelength is \(x \times 10 \mathrm{~cm}^{-1}\). The value of \(x\) is ________ (Integer answer)

$r=k[A]$ for a reaction, $50%$ of $A$ is decomposed in $120$ minutes. The time taken for $90%$ decomposition of $A$ is ______ minutes.