JEE Main 2017 — Physical Chemistry

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:

Among the following species which option contains all isoelectronic species?

An ideal gas undergoes isothermal expansion at constant pressure. During the process:

Consider the following standard electrode potentials (${\text{E}}^{\text{o}}$ in volts) in aqueous solution: $\begin{matrix}\underset{}{\text{E}\text{l}\text{e}\text{m}\text{e}\text{n}\text{t}} & \underset{}{{\text{M}}^{3+}/\text{M}} & \underset{}{{\text{M}}^{+}/\text{M}} \\ \text{A}\text{l} & -1.66 & +0.55 \\ \text{T}\text{l} & +1.26 & -0.34\end{matrix}$ Based on these data, which of the following statements is correct?

Excess of $\mathrm{NaOH}(\mathrm{aq})$ was added to $100\mathrm{mL}$ of ${\mathrm{FeCl}}_{3} (\mathrm{aq})$ resulting into $2.14g$ of $\mathrm{Fe}{(\mathrm{OH})}_{3}$. The molarity of ${\mathrm{FeCl}}_{3}(\mathrm{aq})$ is: (Given the molar mass of$\mathrm{Fe}=56g$${\mathrm{mol}}^{-1}$ and molar mass of $\mathrm{Cl}=35.5 g {\mathrm{mol}}^{-1}$)

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

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:

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:

$1$ 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:

If the shortest wavelength in Lyman series of hydrogen atom is $A$, then the longest wavelength in Paschen series of ${\mathrm{He}}^{+}$ is

$\text{Δ}\text{U}$ is equal to:

${ \text{pK}}_{\text{a}}$ of a weak acid $( \text{HA})$ and ${ \text{pK}}_{\text{b}}$ of a weak base $( \text{BOH})$ are $3.2$ and $3.4$ respectively. The $\text{pH}$ of their salt $( \text{AB})$ solution at ${ \text{25}}^{\text{o}} \text{C}$ is

$50 \mathrm{mL}$ of $0.2M$ ammonia solution is treated with $25\mathrm{mL}\mathrm{of}0.2M\mathrm{HCl}$. If ${\mathrm{pK}}_{b}$ of ammonia solution is $4.75$, the $\mathrm{pH}$ of the mixture will be:

$5g$ of ${\mathrm{Na}}_{2}{\mathrm{SO}}_{4}$ was dissolved in $x g$ of ${H}_{2}O$ . The change in freezing point was found to be $3{.82}^{o}C$ . If ${\mathrm{Na}}_{2}{\mathrm{SO}}_{4}$ is $81.5%$ ionised, the value of $x$ ( ${K}_{f}$ for water $=1{.86}^{o}C \mathrm{kg} {\mathrm{mol}}^{-1}$ ) is approximately: (molar mass of $S=32 g {\mathrm{mol}}^{-1}$ and that of $\mathrm{Na}=23 g {\mathrm{mol}}^{-1}$ )

The electron in the hydrogen atom undergoes transition from higher orbitals to orbital of radius $211.6\mathrm{pm}$. This transition is associated with

The enthalpy change on freezing of $1\mathrm{mol}$ of water at $5^{\circ}C$ to ice at $-5^{\circ}C$ is: (Given ${\Delta }_{\mathrm{fus}} H=6 \mathrm{kJ} {\mathrm{mol}}^{-1}$ at $0^{\circ}C,$ ${C}_{p}({H}_{2}O, l)=75.3 J {\mathrm{mol}}^{-1}{K}^{-1}$ ${C}_{p}({H}_{2}O, s)=36.8 J {\mathrm{mol}}^{-1}{K}^{-1}$ )

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?

The freezing point of benzene decreases by ${0.45}^{^{\circ}}C$ on adding $0.2 g$ of acetic acid to $20g$ of benzene. If acetic acid associates to form a dimer in benzene, then what is the percentage association of acetic acid in benzene? $({K}_{f}\mathrm{for} \mathrm{benzene}=5.12 K \mathrm{kg} {\mathrm{mol}}^{-1} )$

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:

The pair of compounds having metals in their highest oxidation state 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 rate of a reaction quadruples when the temperature changes from $300$ to $310K$ . The activation energy of this reaction is: (Assume Activation energy and pre-exponential factor are independent of temperature; $\mathrm{ln}(2)=0.693;R=8.314J{\mathrm{mol}}^{-1}{K}^{-1}$)

To find the standard potential of ${M}^{3+}/M$ electrode, the following cell is constituted: $\mathrm{Pt}/M/{M}^{3+} (0.001 \mathrm{mol} {L}^{-1})/{\mathrm{Ag}}^{+} (0.01 \mathrm{mol} {L}^{-1})/\mathrm{Ag}$ The emf of the cell is found to be $0.421\mathrm{volt}$ at $298K$. The standard potential of half-reaction ${M}^{3+}+3{e}^{-}\rightarrow M$ at $298K$ will be: (Given: ${E}_{\frac{{\mathrm{Ag}}^{+}}{\mathrm{Ag}}}^{\circleddash }$ at $298K=0.80\mathrm{volt}$)

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 $(R=8.314 J {\mathrm{mol}}^{-1}{K}^{-1})$

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

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?

Which of the following ions does not liberate hydrogen gas on reaction with dilute acids?