Physical Chemistry PYQ — Page 68

Given $$ \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\circ}=0.34 \mathrm{~V}, \mathrm{E}_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\circ}=0.15 \mathrm{~V} $$ Standard electrode potential for the half cell $\mathrm{Cu}^{+} / \mathrm{Cu}$ is

The standard potentials of $\mathrm{Ag}^{+} / \mathrm{Ag}, \mathrm{Hg}_2{ }^{2+} / 2 \mathrm{Hg}$, $\mathrm{Cu}^{2+} / \mathrm{Cu}$ and $\mathrm{Mg}^{2+} / \mathrm{Mg}$ electrodes are $0.80,0.79$, $0.34$ and $-2.37 \mathrm{~V}$, respectively. An aqueous solution which contains one mole per litre of the salts of each of the four metals is electrolyzed. With increasing voltage, the correct sequence of deposition of the metals at the cathode is

The pH of a $0.1$ molar solution of the acid $\mathrm{HQ}$ is $3$ . The value of the ionization constant, Ka of this acid is :

$K_1, K_2$ and $K_3$ are the equilibrium constants of the following reactions (I), (II) and (III) respectively: (I) $\mathrm{N}_2+2 \mathrm{O}_2 \rightleftharpoons 2 \mathrm{NO}_2$ (II) $2 \mathrm{NO}_2 \rightleftharpoons \mathrm{N}_2+2 \mathrm{O}_2$ (III) $\mathrm{NO}_2 \rightleftharpoons \frac{1}{2} \mathrm{~N}_2+\mathrm{O}_2$ The correct relation from the following is

The density of a solution prepared by dissolving $120 \mathrm{~g}$ of urea (mol. Mass $=60 \mathrm{u}$ ) in $1000 \mathrm{~g}$ of water is $1.15 \mathrm{~g} / \mathrm{mL}$. The molarity of this solution is :

One mole of an ideal gas is expanded isothermally and reversibly to half of its initial pressure. $\Delta S$ for the process in $\mathrm{J} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$ is $[\ln 2=0.693$ and $R=8.314, \mathrm{~J} /(\mathrm{mol} \mathrm{K})]$

The electron affinity of chlorine is $3.7 \mathrm{eV} .1$ gram of chlorine is completely converted to $\mathrm{Cl}^{-}$ion in a gaseous state. $\left(1 \mathrm{eV}=23.06 \mathrm{kcal} \mathrm{mol}^{-1}\right)$. Energy released in the process is

If $K_{s p}$ of $\mathrm{CaF}_2$ at $25^{\circ} \mathrm{C}$ is $1.7 \times 10^{-10}$, the combination amongst the following which gives a precipitate of $\mathrm{CaF}_2$ is

$5 \mathrm{~g}$ of benzene on nitration gave $6.6 \mathrm{~g}$ of nitrobenzene. The theoretical yield of the nitrobenzene will be

For a reaction $A \rightarrow$ Products, a plot of $\log t_{1 / 2}$ versus $\log a_0$ is shown in the figure. If the initial concentration of $A$ is represented by $a_0$, the order of the reaction is 

In a chemical reaction $A$ is converted into $B$. The rates of reaction, starting with initial concentrations of $A$ as $2 \times 10^{-3} \mathrm{M}$ and $1 \times 10^{-3}$ $\mathrm{M}$, are equal to $2.40 \times 10^{-4} \mathrm{Ms}^{-1}$ and $0.60 \times 10^{-4} \mathrm{Ms}^{-1}$ respectively. The order of reaction with respect to reactant $A$ will be

For a first order reaction, $(A) \rightarrow$ products, the concentration of $A$ changes from $0.1 \mathrm{~M}$ to $0.025 \mathrm{~M}$ in $40$ minutes. The rate of reaction when the concentration of $A$ is $0.01 \mathrm{~M}$ is :

Reaction rate between two substance $A$ and $B$ is expressed as following: rate $=k[A]^n[B]^m$ If the concentration of $\mathrm{A}$ is doubled and concentration of $\mathrm{B}$ is made half of initial concentration, the ratio of the new rate to the earlier rate will be:

A transition metal $M$ forms a volatile chloride which has a vapour density of $94.8$. If it contains $74.75 \%$ of chlorine the formula of the metal chloride will be

The freezing point of a $1.00 \mathrm{~m}$ aqueous solution of $\mathrm{HF}$ is found to be $-1.91^{\circ} \mathrm{C}$. The freezing point constant of water, $K_f$ is $1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$. The percentage dissociation of $\mathrm{HF}$ at this concentration is

Liquids A and B form an ideal solution. At $30^{\circ} \mathrm{C}$, the total vapour pressure of a solution containing $1 \mathrm{~mol}$ of A and $2 \mathrm{~mol}$ of B is $250 \mathrm{~mm} \mathrm{Hg}$. The total vapour pressure becomes $300 \mathrm{~mm} \mathrm{Hg}$ when 1 more mol of $\mathrm{A}$ is added to the first solution. The vapour pressures of pure $\mathrm{A}$ and $\mathrm{B}$ at the same temperature are

One mole of $\mathrm{O}_{2(\mathrm{~g})}$ and two moles of $\mathrm{SO}_{2(\mathrm{~g})}$ were heated in a closed vessel of one-litre capacity at $1098 \mathrm{~K}$. At equilibrium $1.6$ moles of $\mathrm{SO}_{3(\mathrm{~g})}$ were found. The equilibrium constant $K_c$ of the reaction would be

The activation energy for a reaction which doubles the rate when the temperature is raised from $298 \mathrm{~K}$ to $308 \mathrm{~K}$ is

The value of $K_p$ for the equilibrium reaction $\mathrm{N}_2 \mathrm{O}_4(g) \rightleftharpoons 2 \mathrm{NO}_2(g)$ is 2 . The percentage dissociation of $\mathrm{N}_2 \mathrm{O}_4(g)$ at a pressure of $0.5 \mathrm{~atm}$ is

The following sets of quantum numbers represent four electrons in an atom. (i) $n=4, l=1$ (ii) $n=4, l=0$ (iii) $n=3, l=2$ (iv) $n=3, l=1$ The sequence representing increasing order of energy, is

Given (i) $\operatorname{HCN}(a q)+\mathrm{H}_2 \mathrm{O}(b) \rightleftharpoons \mathrm{H}_3 \mathrm{O}^{+}(a q)+\mathrm{CN}^{-}(a q)$ $K_{\mathrm{a}}=6.2 \times 10^{-10}$ (ii) $\mathrm{CN}^{-}(a q)+\mathrm{H}_2 \mathrm{O}(\mathrm{l}) \rightleftharpoons \mathrm{HCN}(a q)+\mathrm{OH}^{-}(a q)$ $K_{\mathrm{b}}=1.6 \times 10^{-5}$. These equilibria show the following order of the relative base strength,

The concentrated sulphuric acid that is peddled commercial is $95 \% \mathrm{H}_2 \mathrm{SO}_4$ by weight. If the density of this commercial acid is $1.834 \mathrm{~g} \mathrm{~cm}^{-3}$, the molarity of this solution is

The standard reduction potentials for $\mathrm{Zn}^{2+} / \mathrm{Zn}, \mathrm{Ni}^{2+} / \mathrm{Ni}$, and $\mathrm{Fe}^{2+} / \mathrm{Fe}$ are $-0.76,-0.23$ and $-0.44 \mathrm{~V}$ respectively. The reaction $\mathrm{X}+\mathrm{Y}^{2+} \rightarrow \mathrm{X}^{2+}+\mathrm{Y}$ will be spontaneous when:

The electrons identified by quantum numbers $\mathrm{n}$ and $\mathrm{I}$ : (a) $n=4, I=1$ (b) $n=4, l=0$ (c) $n=3, I=2$ (d) $n=3, I=1$ Can be placed in order of increasing energy as: