Physical Chemistry PYQ — Page 61

Two reactions ${A}_{1}$ and ${A}_{2}$ have identical pre-exponential factors. The activation energy of ${A}_{1}$ is more than ${A}_{2}$ by $10\mathrm{kJ}{\mathrm{mol}}^{-1}$ . If ${k}_{1}$ and ${k}_{2}$ are the rate constants for reactions ${A}_{1}$ and ${A}_{2}$, respectively at $300K$, then $\mathrm{ln}⁡(\frac{{k}_{2}}{{k}_{1}})$ is equal to $(R=8.314 J {\mathrm{mol}}^{-1}{K}^{-1})$

$1$ gram of a carbonate $({M}_{2}{\mathrm{CO}}_{3})$ on treatment with excess $\mathrm{HCl}$ produces $0.01186$ moles of ${\mathrm{CO}}_{2}$ . The molar mass of ${M}_{2}{\mathrm{CO}}_{3}$ in ${\mathrm{gmol}}^{-1}$ is:

For a reaction, $A(g)\rightarrow A(l);\Delta H=-3\mathrm{RT}.$ The correct statement for the reaction is

Given: $C(\mathrm{graphite})+{O}_{2}(g)\rightarrow {\mathrm{CO}}_{2}(g) ;{\Delta }_{r}{H}^{o}=-393.5\mathrm{kJ}{\mathrm{mol}}^{-1}$ ${H}_{2}(g)+\frac{1}{2}{O}_{2}(g)\rightarrow {H}_{2}O(l);{\Delta }_{r}{H}^{o}=-285.8 \mathrm{kJ} {\mathrm{mol}}^{-1}$ ${\mathrm{CO}}_{2}(g)+2{H}_{2}O(l)\rightarrow {\mathrm{CH}}_{4}(g)+2{O}_{2}(g);{\Delta }_{r}{H}^{o}=+890.3 \mathrm{kJ} {\mathrm{mol}}^{-1}$ Based on the above thermochemical equations, the value of ${\Delta }_{r}{H}^{o}$ at $298K$ for the reaction $C(\mathrm{graphite})+2{H}_{2}(g)\rightarrow {\mathrm{CH}}_{4}(g)$ will be:

Given ${E}_{{\mathrm{Cl}}_{2}/{\mathrm{Cl}}^{-}}^{o}=1.36V, {E}_{{\mathrm{Cr}}^{3+}/\mathrm{Cr}}^{o}= -0.74V$ ${E}_{{\mathrm{Cr}}_{2}{O}_{7}^{2-}/{\mathrm{Cr}}^{3+}}^{o}=1.33V, {E}_{{\mathrm{MnO}}_{4}^{-}/{\mathrm{Mn}}^{2+}}^{o}=1.51V.$ Among the following, the strongest reducing agent is:

The radius of the second Bohr orbit for hydrogen atom is (Planck's constant, $(h)=6.6262\times {10}^{-34}\mathrm{Js};$ mass of electron $=9.1091\times {10}^{-31}\mathrm{kg};$ charge of electron $=1.60210\times {10}^{-19}C;$ permittivity of vacuum, $({\in }_{0})=8.854185\times {10}^{-12}{\mathrm{kg}}^{-1}{m}^{-3}{A}^{2}$)

The rate of a reaction A doubles on increasing the temperature from$300\mathrm{to}310K$. By how much, the temperature of reaction B should be increased from $300K$ so that rate doubles if activation energy of the reaction B is twice to that of reaction A.

The following reaction occurs in the Blast Furnace where iron ore is reduced to iron metal: $\text{F}{\text{e}}_{2}{\text{O}}_{3}(\text{s})+3\text{C}\text{O}(\text{g}) \rightleftharpoons 2\text{F}\text{e} (\text{l})+3\text{C}{\text{O}}_{2}(\text{g})$ Using the Le Chatelier's principle, predict which one of the following will not disturb the equilibrium?

A solution is prepared by mixing $8.5$ g of ${\mathrm{CH}}_{2}{\mathrm{Cl}}_{2}$ and $11.95 \text{g}$ of ${\mathrm{CHCl}}_{3}$ . If vapour pressure of ${\mathrm{CH}}_{2}{\mathrm{Cl}}_{2}$ and ${\mathrm{CHCl}}_{3}$ at $298$K are $415$ and $200$ mm Hg respectively, the mole fraction of ${\mathrm{CHCl}}_{3}$ in vapour form is: $(\text{M}\text{o}\text{l}\text{a}\text{r} \text{m}\text{a}\text{s}\text{s} \text{o}\text{f} \mathrm{Cl}=35.5 \text{g} \text{m}\text{o}{\text{l}}^{-1})$

Addition of sodium hydroxide solution to a weak acid (HA) results in a buffer of pH 6. If ionization constant of HA is ${10}^{-5}$, the ratio of salt to acid concentration in the buffer solution will be:

What quantity (in $\mathrm{mL}$) of a $45%$ acid solution of a mono-protic strong acid must be mixed with a $20%$ solution of the same acid to produce $800\mathrm{mL}$ of a $29.875%$ acid solution?

What is the standard reduction potential $({E}^{o})$ for ${\mathrm{Fe}}^{3+}\rightarrow \mathrm{Fe}?$ Given that: ${\mathrm{Fe}}^{2+}+2{e}^{-}\rightarrow \mathrm{Fe};{E}_{{\mathrm{Fe}}^{2+}/\mathrm{Fe}}^{o}=-0.47V$ ${\mathrm{Fe}}^{3+}+{e}^{-}\rightarrow {\mathrm{Fe}}^{2+};{E}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}^{o}=+0.77V$

The most abundant elements by mass in the body of a healthy human adult are: Oxygen (61.4%); Carbon (22.9%), Hydrogen (10.0%); and Nitrogen (2.6%). The weight which a 75kg person would gain if all ${ }^{1}H$ atoms are replaced by ${ }^{2}H$ atoms is:

A reaction at 1 bar is non-spontaneous at low temperature but becomes spontaneous at high temperature. Identify the correct statement about the reaction among the following:

What will happen when a block of copper metal is dropped into a beaker containing a solution of $1 \text{M}$ $ZnS{O}_{4}$?

The volume of 0.1 M strong dibasic acid sufficient to neutralize 1g of a base that furnishes 0.04 mole of $O{H}^{-}$ in aqueous solution is :

Oxidation of succinate ion produces ethylene and carbon dioxide gases. On passing $0.2$ Faraday electricity through an aqueous solution of potassium succinate, what is the total volume of gases (at both cathode and anode) at STP ($1\mathrm{atm}$ and $273K$)?

A stream of electrons from a heat filament was passed between two charge plates kept at a potential difference $V\mathrm{esu}$. If $e$ and $m$ are charge and mass of an electron, respectively, then the value of $\frac{h}{\lambda }$ (where $\lambda$ is wavelength associated with the electron wave) is given by:

At $300K$ and $1\mathrm{atm}$, $15\mathrm{mL}$ of a gaseous hydrocarbon requires $375\mathrm{mL}$ air containing $20%{O}_{2}$ by volume, for complete combustion. After combustion, the gases occupy $345\mathrm{mL}$. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is: (Assume complete combustion of reactant)

The total number of orbitals associated with the principal quantum number $5$ is:

For the reaction, $A(g)+B(g)\rightarrow C(g)+D(g), \Delta {H}^{o}$ and $\Delta {S}^{o}$ are, respectively, $-29.8 kJ mo{l}^{-1}$ and $-0.100 kJ {K}^{-1} mo{l}^{-1}$ at 298 K. The equilibrium constant for the reaction at 298 k is:

Decomposition of ${H}_{2}{O}_{2}$ follows a first order reaction. In fifty minutes the concentration of ${\text{H}}_{2} {\text{O}}_{2}$ decreases from $0.5$ to $0.125 M$ in one such decomposition. When the concentration of ${H}_{2}{O}_{2}$ reaches $0.05 M$ , the rate of formation of ${O}_{2}$ will be:

An organic compound contains $C,H$ and $S$. The minimum molecular weight of the compound containing $8%$ Sulphur is

$18g$ glucose $({C}_{6}{H}_{12}{O}_{6})$ is added to $178.2g$ water. The vapour pressure of water (in torr) for this aqueous solution is: