Physical Chemistry PYQ — Page 14

Vapour pressure of chloroform $\left(\mathrm{CHCl}_3\right)$ and dichloromethane $\left(\mathrm{CH}_2 \mathrm{Cl}_2\right)$ at $25^{\circ} \mathrm{C}$ are $200 \mathrm{~mm} \mathrm{Hg}$ and $415 \mathrm{~mm} \mathrm{Hg}$ respectively. Vapour pressure of the solution obtained by mixing $25.5 \mathrm{~g}$ of $\mathrm{CHCl}_3$ and $4 \mathrm{O} \mathrm{g}$ of $\mathrm{CH}_2 \mathrm{Cl}_2$ at the same temperature will be: [Molecular mass of $\mathrm{CHCl}_3=119.5 \mathrm{~g} / \mathrm{mol}$ and molecular mass of $\mathrm{CH}_2 \mathrm{Cl}_2=85 \mathrm{~g} / \mathrm{mol}$ ]

In a zero order reaction for every $10^{\circ}$ rise of temperature, the rate is doubled. If the temperature is increased from $10^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$, the rate of the reaction will become

The orbital angular momentum of a p-electron is given as

Standard reduction potentials of the half reactions are given below $$ \begin{array}{ll} \mathrm{F}_2(g)+2 e^{-} \longrightarrow 2 \mathrm{~F}^{-}(a q) ; & E^{\circ}=+2.85 \mathrm{~V} \\ \mathrm{Cl}_2(g)+2 e^{-} \longrightarrow 2 \mathrm{Cl}^{-}(a q) ; & E^{\circ}=+1.36 \mathrm{~V} \\ \mathrm{Br}_2(l)+2 e^{-} \longrightarrow 2 \mathrm{Br}^{-}(a q) ; & E^{\circ}=+1.06 \mathrm{~V} \\ \mathrm{I}_2(s)+2 e^{-} \longrightarrow 2 \mathrm{I}^{-}(a q) ; & E^{\circ}=+0.53 \mathrm{~V} \end{array} $$ The strongest oxidising and reducing agents respectively are

Given the reaction between two gases represented by $A_2$ and $B_2$ to give the compound $A B(g)$. $$ A_2(g)+B_2(g) \rightleftharpoons 2 A B(g) $$ At equilibrium, the concentration of $A_2=3.0 \times 10^{-3} \mathrm{M}$ of $B_2=4.2 \times 10^{-3} \mathrm{M}$ of $A B=2.8 \times 10^{-3} \mathrm{M}$ If the reaction takes place in a sealed vessel at $527^{\circ} \mathrm{C}$, then the value of $K_c$ will be

Molar conductivities $\left(\Lambda_m^{\circ}\right)$ at infinite dilution of $\mathrm{NaCl}, \mathrm{HCl}$ and $\mathrm{CH}_3 \mathrm{COONa}$ are 126.4, 425.9 and $91.0 \mathrm{~S} \mathrm{~cm} \mathrm{cmol}^{-1}$ respectively. $\Lambda^{\circ}{ }_m$ for $\mathrm{CH}_3 \mathrm{COOH}$ will be

Buffer solutions have constant acidity and alkalinity because

Given that the equilibrium constant for the reaction, $$ 2 \mathrm{SO}_2(g)+\mathrm{O}_2(g) \rightleftharpoons 2 \mathrm{SO}_3(g) $$ has a value of 278 at a particular temperature. What is the value of the equilibrium constant for the following reaction at the same temperature? $$ \mathrm{SO}_3(g) \rightleftharpoons \mathrm{SO}_2(g)+\frac{1}{2} \mathrm{O}_2(g) $$

Activation energy $\left(E_a\right)$ and rate constants $\left(k_1\right.$ and $\left.k_2\right)$ of a chemical reaction at two different temperatures $\left(T_1\right.$ and $\left.T_2\right)$ are related by

$\mathrm{pH}$ of a saturated solution of $\mathrm{Ba}(\mathrm{OH})_2$ is 12. The value of solubility product $K_{\text {sp }}$ of $\mathrm{Ba}(\mathrm{OH})_2$ is

The Gibbs' energy for the decomposition of $\mathrm{Al}_2 \mathrm{O}_3$ at $500^{\circ} \mathrm{C}$ is as follows $$ \begin{gathered} \frac{2}{3} \mathrm{Al}_2 \mathrm{O}_3 \longrightarrow \frac{4}{3} \mathrm{Al}+\mathrm{O}_2 ; \\ \Delta_r G=+960 \mathrm{~kJ} \mathrm{~mol}^{-1} \end{gathered} $$ The potential difference needed for the electrolytic reduction of aluminium oxide $\left(\mathrm{Al}_2 \mathrm{O}_3\right)$ at $500^{\circ} \mathrm{C}$ is at least

Maximum number of electrons in a subshell with $l=3$ and $n=4$ is

Limiting molar conductivity of $\mathrm{NH}_4 \mathrm{OH~} \left( \text{i.e., } \stackrel{\circ}{\Lambda}_{m\left(\mathrm{NH}_4 \mathrm{OH}\right)}\right)$ is equal to

Standard electrode potential of three metals $X, Y$ and $Z$ are $-1.2 \mathrm{~V},+0.5 \mathrm{~V}$ and $-3.0 \mathrm{~V}$ respectively. The reducing power of these metals will be

Which one of the following statements is not true?

Which one of the following statements for the order of a reaction is incorrect?

The electrode potentials for $\begin{aligned} & \mathrm{Cu}^{2+}(a q)+e^{-} \longrightarrow \mathrm{Cu}^{+}(a q) \\ & \text { and } \mathrm{Cu}^{+}(a q)+e^{-} \longrightarrow \mathrm{Cu}(s) \\ & \text { are }+0.15 \mathrm{~V} \text { and }+0.50 \mathrm{~V} \text { respectively. The value } \\ & \text { of } E_{\mathrm{Cu}^{2+} / \mathrm{Cu}}^{\circ} \text { will be } \end{aligned}$

A solution contains $\mathrm{Fe}^{2+}, \mathrm{Fe}^{3+}$ and $\mathrm{I}^{-}$ions. This solution was treated with iodine at $35^{\circ} \mathrm{C}$. $E^{\circ}$ for $\mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}$ is $+0.77 \mathrm{~V}$ and $\mathrm{E}^{\circ}$ for $\mathrm{I}_2 / 2 \mathrm{I}^{-}=0.536 \mathrm{~V}$. The favourable redox reaction is

If $x$ is amount of adsorbate and $m$ is amount of adsorbent, which of the following relations is not related to adsorption process?

The value of $\Delta H$ for the raction $X_2(g)+4 Y_2(g)^{39} 2 X Y_4(g)$ is less than zero. Formation of $X Y_4(g)$ will be favoured at

The freezing point depression constant for water is $-1.86^{\circ} \mathrm{C} \mathrm{m}^{-1}$. If $5.00 \mathrm{~g} \mathrm{Na} \mathrm{SO}_4$ is dissolved in $45.0 \mathrm{~g} \mathrm{H}_2 \mathrm{O}$, the freezing point is changed by $-3.82^{\circ} \mathrm{C}$. Calculate the van't Hoff factor for $\mathrm{Na}_2 \mathrm{SO}_4$.

A 0.1 molal aqueous solution of a weak acid is $30 \%$ ionised. If $K_f$ for water is $1.86^{\circ} \mathrm{C} / \mathrm{m}$, the freezing point of the solution will be

Which of the following is correct option for free expansion of an ideal gas under adiabatic condition?

By what factor does the average velocity of a gaseous molecule increase when the temperature (in Kelvin) is doubled?