JEE Main 2008 — Physical Chemistry

Oxidising power of chlorine in aqueous solution can be determined by the parameters indicated below: $$ \frac{1}{2} \mathrm{Cl}_2(\mathrm{~g}) \stackrel{\frac{1}{2} \Delta_{\mathrm{ass}} \mathrm{H}^{\ominus}}{\longrightarrow} \mathrm{Cl}(\mathrm{g}) \stackrel{\Delta_{\mathrm{eg} H^{\ominus}}}{\longrightarrow} \mathrm{Cl}^{-}(\mathrm{g}) \stackrel{\Delta_{\mathrm{m} \mathrm{on}^{H^{\ominus}}}^{\longrightarrow}}{\longrightarrow} \mathrm{Cl}^{-}(\mathrm{aq}) . $$ The energy involved in the conversion of $\frac{1}{2} \mathrm{Cl}_2(\mathrm{~g})$ to $\mathrm{Cl}^{-}(\mathrm{g})$ (using the data, $\left.\Delta_{\text {diss }} H_{\mathrm{Cl}_2}^{\ominus}=240 \mathrm{kJmol}^{-1}, \Delta_{\mathrm{eg}} H_{\mathrm{cl}}^{\ominus}=-349 \mathrm{kJmol}^{-1}, \Delta_{\mathrm{hyd}} \mathrm{H}_{\mathrm{Cl}}^{\ominus}=-381 \mathrm{kJmol}^{-1}\right)$ will be

For a reaction $\frac{1}{2} A \rightarrow 2 B$, rate of disappearance of ' $A$ ' is related to the rate of appearance of 'B' by the expression

The $\mathrm{pK}_{\mathrm{a}}$ of a weak acid, $\mathrm{HA}$, is $4.80$. The $\mathrm{pK}_{\mathrm{b}}$ of a weak base, $\mathrm{BOH}$, is $4.78$. The $\mathrm{pH}$ of an aqueous solution of the corresponding salt, BA, will be

At $80^{\circ} \mathrm{C}$, the vapour pressure of pure liquid ' $A$ ' is $520 \mathrm{~mm} \mathrm{Hg}$ and that of pure liquid ' $B$ ' is $1000 \mathrm{~mm}$ $\mathrm{Hg}$. If a mixture solution of ' $A$ ' and ' $B$ ' boils at $80^{\circ} \mathrm{C}$ and $1 \mathrm{~atm}$ pressure, the amount of ' $A$ ' in the mixture is $(1 \mathrm{~atm}=760 \mathrm{~mm} \mathrm{Hg})$

The equilibrium constants $K_{P_1}$ and $K_{P_2}$ for the reactions $X \rightleftharpoons 2 Y$ and $Z \rightleftharpoons P+Q$, respectively are in the ratio of $1: 9$. If the degree of dissociation of $X$ and $Z$ be equal then the ratio of total pressure at these equilibria is

The vapour pressure of water at $20^{\circ} \mathrm{C}$ is $17.5 \mathrm{~mm} \mathrm{Hg}$. If $18 \mathrm{~g}$ of glucose $\left(\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6\right)$ is added to $178.2 \mathrm{~g}$ of water at $20^{\circ} \mathrm{C}$, the vapour pressure of the resulting solution will be

For the following three reactions $a, b$ and $c$, equilibrium constants are given: a. $\mathrm{CO}(\mathrm{g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{CO}_2(\mathrm{~g})+\mathrm{H}_2(\mathrm{~g}) ; \quad \mathrm{K}_1$ b. $\mathrm{CH}_4(\mathrm{~g})+\mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{CO}(\mathrm{g})+3 \mathrm{H}_2(\mathrm{~g}) ; \quad \mathrm{K}_2$ c. $\mathrm{CH}_4(\mathrm{~g})+2 \mathrm{H}_2 \mathrm{O}(\mathrm{g}) \rightleftharpoons \mathrm{CO}_2(\mathrm{~g})+4 \mathrm{H}_2(\mathrm{~g}) ; \mathrm{K}_3$ Which of the following relations is correct?

Which one of the following constitutes a group of the isoelectronic species?

Standard entropy of $X_2, Y_2$ and $X Y_3$ are 60,40 and $50 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$, respectively. For the reaction, $\frac{1}{2} X_2+\frac{3}{2} Y_2 \rightarrow X Y_3, \Delta \mathrm{H}=-30 \mathrm{~kJ}$, to be at equilibrium, the temperature will be

Given $\mathrm{E}_{\mathrm{Cr}^3+/ \mathrm{Cr}}^{\circ}=-0.72 \mathrm{~V}, \mathrm{E}_{\mathrm{Fe}^{2+/ / \mathrm{Fe}}}^{\circ}=-0.42 \mathrm{~V}$. The potential for the cell $\mathrm{Cr}\left|\mathrm{Cr}^{3+}(0.1 \mathrm{M})\right|\left|\mathrm{Fe}^{2+}(0.01 \mathrm{M})\right| \mathrm{Fe}$ is

Four species are listed below i. $\mathrm{HCO}_3^{-}$ ii. $\mathrm{H}_3 \mathrm{O}^{+}$ iii. $\mathrm{HSO}_4^{-}$ iv. $\mathrm{HSO}_3 \mathrm{~F}$ Which one of the following is the correct sequence of their acid strength?

The ionization enthalpy of hydrogen atom is $1.312 \times 10^6 \mathrm{Jmol}^{-1}$. The energy required to excite the electron in the atom from $n=1$ to $n=2$ is