Physical Chemistry PYQ — Page 28

Number of hydrogen atoms per molecule of a hydrocarbon A having $85.8%$ carbon is (Given : Molar mass of $A=84g{\mathrm{mol}}^{-1}$ )

A solution containing $2g$ of a non-volatile solute in $20g$ of water boils at $373.52K$. The molecular mass of the solute is _____ ${\mathrm{gmol}}^{-1}$. (Nearest integer) Given, water boils at $373K,{K}_{b}$ for water $=0.52K\mathrm{kg}{\mathrm{mol}}^{-1}$

The number of correct statements from the following is........... A. ${E}_{\mathrm{cell}}$ is an intensive parameter B. A negative ${E}^{o}$ means that the redox couple is a stronger reducing agent than the ${H}^{+}/{H}_{2}$ couple. C. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. D. The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.

The reaction occurs in which of the given galvanic cell? $\frac{1}{2}{H}_{2}(g)+\mathrm{AgCl}(s)\rightleftharpoons {H}^{+}(\mathrm{aq})+{\mathrm{Cl}}^{-}(\mathrm{aq})+\mathrm{Ag}(s)$

The standard electrode potential of ${M}^{+}/M$ in aqueous solution does not depend on

Following figure shows dependence of molar conductance of two electrolytes on concentration. ${\Lambda }_{m}^{0}$ is the limiting molar conductivity.  The number of Incorrect statement(s) from the following is _____ (A) ${\Lambda }_{m}^{0}$ for electrolyte $A$ is obtained by extrapolation (B) For electrolyte $B,{\Lambda }_{m}\mathrm{Vs}\sqrt{c}$ graph is a straight line with intercept equal to ${\Lambda }_{m}^{0}$ (C) At infinite dilution, the value of degree of dissociation approach zero for electrolyte $B$. (D) ${\Lambda }_{m}$ for any electrolyte $A$ or $B$ can be calculated using $\lambda ^{\circ}$ for individual ions.

The effect of addition of helium gas to the following reaction in equilibrium state at constant volume, is : ${\mathrm{PCI}}_{5}(g)\rightleftharpoons {\mathrm{PCl}}_{3}(g)+{\mathrm{Cl}}_{2}(g)$

For conversion of compound $A\rightarrow B$, the rate constant of the reaction was found to be $4.6\times {10}^{-5}\mathrm{Lmol}-1{s}^{-1}$. The order of the reaction is _____ .

The number of correct statements from the following is ........... A. For $1s$ orbital, the probability density is maximum at the nucleus B. For $2s$ orbital, the probability density first increases to maximum and then decreases sharply to zero. C. Boundary surface diagrams of the orbitals encloses a region of $100%$ probability of finding the electron. D. $p$ and $d$-orbitals have $1$ and $2$ angular nodes respectively E. probability density of $p$-orbital is zero at the nucleus

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : An aqueous solution of $\mathrm{KOH}$ when for volumetric analysis, its concentration should be checked before the use. Reason (R) : On aging,$\mathrm{KOH}$ solution absorbs atmospheric ${\mathrm{CO}}_{2}$. In the light of the above statements, choose the correct answer from the options given below.

The equilibrium constant for the reaction $\mathrm{Zn}(s)+{\mathrm{Sn}}^{2+}(\mathrm{aq})\rightleftharpoons {\mathrm{Zn}}^{2+}(\mathrm{aq})+\mathrm{Sn}(s)$ is $1\times {10}^{20}$ at $298K$. The magnitude of standard electrode potential of $\mathrm{Sn}/{\mathrm{Sn}}^{2+}$ if ${E}_{{\mathrm{Zn}}^{2*}/\mathrm{Zn}}^{0}=-0.76V$ is _____ $\times {10}^{-2}V$. (Nearest integer) Given : $\frac{2.303\mathrm{RT}}{F}=0.059V$

Assume carbon burns according to following equation : $2C(s)+{O}_{2}(g)\rightarrow 2\mathrm{CO}\text{ (s) }$ when $12g$ carbon is burnt in $48g$ of oxygen, the volume of carbon monoxide produced is $______\times {10}^{-1}L$ at STP [nearest integer] [Given : Assume $\mathrm{CO}$ as ideal gas, Mass of $C$ is $12g{\mathrm{mol}}^{-1}$, mass of $O$ is $16g{\mathrm{mol}}^{-1}$ and molar volume of an idal gas at STP is $22.7L{\mathrm{mol}}^{-1}$ ]

The correct reaction profile diagram for a positive catalyst reaction.

The volume of hydrogen liberated at STP by treating $2.4g$ of magnesium with excess of hydrochloric acid is ......$\times {10}^{-2}L$. Given Molar volume of gas is $22.4L$ at STP. Molar mass of magnesium is $24g{\mathrm{mol}}^{-1}$

$80$ mole percent of ${\mathrm{MgCl}}_{2}$ is dissociated in aqueous solution. The vapour pressure of $1.0$ molal aqueous solution of ${\mathrm{MgCl}}_{2}$ at ${38}^{o}C$ is _____ $\mathrm{mm}\mathrm{Hg}$. (Nearest integer) Given: Vapour pressure of water at ${38}^{o}C$ is $50\mathrm{mm}\mathrm{Hg}$

For the first order reaction $A\rightarrow B$ the half life is $30\mathrm{min}$. The time taken for $75%$ completion of the reaction is mm. (Nearest integer) Given : $\mathrm{log}2=0.3010$ $\mathrm{log}3=0.4771$ $\mathrm{log}5=0.6989$

Water decomposes at $2300K$ ${H}_{2}O(g)\rightarrow {H}_{2}(g)+\frac{1}{2}{O}_{2}(g)$ The percent of water decomposing at $2300K$ and 1 bar is _____ (Nearest integer). Equilibrium constant for the reaction is $2\times {10}^{-3}$ at $2300K$

A molecule undergoes two independent first order reactions whose respective half lives are $12\mathrm{min}$ and $3\mathrm{min}$. If both the reactions are occurring then the time taken for the $50%$ consumption of the reactant is ______ $\mathrm{min}$. (Nearest integer)

$A\rightarrow B$ The rate constants of the above reaction at $200K$ and $300K$ are $0.03{\mathrm{min}}^{-1}$ and $0.05{\mathrm{min}}^{-1}$ respectively. The activation energy for the reaction is $J$ (Nearest integer) (Given : In $10=2.3$ $R=8.3J{K}^{-1}{\mathrm{mol}}^{-1}$ $\mathrm{log}5=0.70$ $\mathrm{log}3=0.48$ $\mathrm{log}2=0.30$

Which one of the following sets of ions represents a collection of isoelectronic species? (Given : Atomic Number $:F:9,\mathrm{Cl}:17,\mathrm{Na}=11$ $\mathrm{Mg}=12,\mathrm{Al}=13,K=19,\mathrm{Ca}=20,\mathrm{Sc}=21)$

$0.004M{K}_{2}{\mathrm{SO}}_{4}$ solution is isotonic with $0.01M$ glucose solution. Percentage dissociation of ${K}_{2}{\mathrm{SO}}_{4}$ is _____ (Nearest integer)

A litre of buffer solution contains $0.1$ mole of each of ${\mathrm{NH}}_{3}$ and ${\mathrm{NH}}_{4}\mathrm{Cl}$. On the addition of $0.02$ mole of $\mathrm{HCl}$ by dissolving gaseous $\mathrm{HCl}$, the $\mathrm{pH}$ of the solution is found to be $_____\times {10}^{-3}$ (Nearest integer) Given: ${\mathrm{pK}}_{b}({\mathrm{NH}}_{3})=4.745$ $\mathrm{log}2=0.301$ $\mathrm{log}3=0.477$ $T=298K]$

For the adsorption of hydrogen on platinum, the activation energy is $30\mathrm{kJ}{\mathrm{mol}}^{–1}$ and for the adsorption of hydrogen on nickel, the activation energy is $41.4\mathrm{kJ}{\mathrm{mol}}^{–1}.$ The logarithm of the ratio of the rates of chemisorption on equal areas of the metals at $300K$ is $_______$ (Nearest integer) Given: $\mathrm{In}10=2.3$ $R=8.3J{K}^{-1}{\mathrm{mol}}^{-1}$

For a chemical reaction $A+B\rightarrow$ Product, the order is $1$ with respect to $A$ and $B$.<table class="pyq-table"><tbody><tr><td>Rate $\mathrm{mol}{L}^{-1}{S}^{-1}$</td><td>[A] $\mathrm{mol}{L}^{-1}$</td><td>[B] $\mathrm{mol}{L}^{-1}$</td></tr><tr><td>$0.10$</td><td>$20$</td><td>$0.5$</td></tr><tr><td>$0.40$</td><td>$x$</td><td>$0.5$</td></tr><tr><td>$0.80$</td><td>$40$</td><td>$y$</td></tr></tbody></table>What is the value of $x$ and $y$?