NEET UG Chemistry — Physical Chemistry previous year questions with solutions.
When electromagnetic radiation of wavelength $300 \mathrm{~nm}$ falls on the surface of a metal, electrons are emitted with the kinetic energy of $1.68 \times 10^5$ $\mathrm{J} \mathrm{mol}^{-1}$. What is the minimum energy needed to remove an electron from the metal? $\begin{aligned} & \left(h=6.626 \times 10^{-34} \mathrm{Js}, \mathrm{c}=3 \times 10^8 \mathrm{~ms}^{-1},\right. \\ & \mathrm{N}_{\mathrm{A}}=6.022 \times 10^{23} \mathrm{~mol}^{-1} \end{aligned}$
$\mathrm{K}_{\mathrm{H}}$ value for some gases at the same temperature ' $\mathrm{T}$ ' are given: $\begin{array}{c|c} \text {gas } & \mathrm{K}_{\mathrm{H}} / \mathbf{k} \text { bar } \\ \hline \mathrm{Ar} & 40.3 \\ \mathrm{CO}_2 & 1.67 \\ \mathrm{HCHO} & 1.83 \times 10^{-5} \\ \mathrm{CH}_4 & 0.413 \end{array}$ where $\mathrm{K}_{\mathrm{H}}$ is Henry's Law constant in water. The order of their solubility in water is :
Given below are half cell reactions : ${\mathrm{MnO}}_{4}^{-}+8{H}^{+}+5{e}^{-}\rightarrow {\mathrm{Mn}}^{2+}+4{H}_{2}O$, ${E}_{{\mathrm{Mn}}^{2+}/{\mathrm{MnO}}_{4}^{-}}^{o}=-1.510V$ $\frac{1}{2}{O}_{2}+2{H}^{+}+2{e}^{-}\rightarrow {H}_{2}O$ ${E}_{{O}_{2}/{H}_{2}O}^{o}=+1.223V$ Will the permanganate ion, ${\mathrm{MnO}}_{4}^{-}$ liberate ${O}_{2}$ from water in the presence of an acid?
Identify the incorrect statement from the following.
Which of the following $p-V$ curve represents maximum work done?
The given graph is a representation of kinetics of a reaction.  The $y$ and $x$ axes for zero and first order reactions, respectively are
For a first order reaction $A\rightarrow$ Products, initial concentration of $A$ is $0.1M$, which becomes $0.001M$ after $5$ minutes. Rate constant for the reaction in ${\mathrm{min}}^{-1}$ is
If radius of second Bohr orbit of the ${\mathrm{He}}^{+}$ ion is $105.8\mathrm{pm}$, what is the radius of third Bohr orbit of ${\mathrm{Li}}^{2+}$ ion?
The rate of a first order reaction depends on
At $298K$, the standard electrode potentials of ${\mathrm{Cu}}^{2+}/\mathrm{Cu},{\mathrm{Zn}}^{2+}/\mathrm{Zn},{\mathrm{Fe}}^{2+}/\mathrm{Fe}$ and ${\mathrm{Ag}}^{+}/\mathrm{Ag}$ are $0.34V$, $-0.76V$, $-0.44V$ and $0.80V$, respectively. On the basis of standard electrode potential, predict which of the following reaction cannot occur?
Which of the following reactions is a decomposition redox reaction?
Standard electrode potential for the cell with cell reaction $\mathrm{Zn}(\mathrm{s})+\mathrm{Cu}^{2+}(\mathrm{aq}) \longrightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{Cu}(\mathrm{s})$ is $1.1 \mathrm{~V}$. Calculate the standard gibbs energy change for the cell reaction. (Given $\mathrm{F}=96487 \mathrm{C} \mathrm{mol}^{-1}$ )
For a chemical reaction $4 \mathrm{~A}+3 \mathrm{~B} \rightarrow 6 \mathrm{C}+9 \mathrm{D}$ rate of formation of $\mathrm{C}$ is $6 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$ and rate of disappearance of $\mathrm{A}$ is $4 \times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1} \mathrm{~s}^{-1}$. The rate of reaction and amount of $B$ consumed in interval of 10 seconds, respectively will be:
$K_P$ for the following reaction is 3.0 at $1000 \mathrm{~K}$. $\mathrm{CO}_2(\mathrm{~g})+\mathrm{C}(\mathrm{s}) \rightleftharpoons 2 \mathrm{CO}(\mathrm{g})$ What will be the value of $\mathrm{K}_C$ for the reaction at the same temperature? (Given: $\mathrm{R}=0.083 \mathrm{~L} \mathrm{bar} \mathrm{K}^{-1} \mathrm{~mol}^{-1}$ )
In one molal solution that contains $0.5$ mole of a solute, there is
$0.01 \mathrm{M}$ acetic acid solution is $1 \%$ ionised, then $\mathrm{pH}$ of this acetic acid solution is :
A particular station of All India Radio, New Delhi, broadcasts on a frequency of $1,368\mathrm{kHz}$ (kilo Hertz). The wavelength of the electromagnetic radiation emitted by the transmitter is [speed of light, $c=3.0\times {10}^{8}{\mathrm{ms}}^{-1}$]
From the following pairs of ions which one is not an iso-electronic pair?
The correct option for the value of vapour pressure of a solution at $45ºC$ with benzene to octane in molar ratio $3:2$ is: [At $45^{\circ}C$ vapour pressure of benzene is $280\mathrm{mm}\mathrm{Hg}$ and that of octane is $420\mathrm{mm}\mathrm{Hg}.$ Assume Ideal gas]
For a reaction $A\rightarrow B,$ enthalpy of reaction is $-4.2\mathrm{kJ}{\mathrm{mol}}^{-1}$ and enthalpy of activation is $9.6\mathrm{kJ}{\mathrm{mol}}^{-1}.$ The correct potential energy profile for the reaction is shown in the option.
For irreversible expansion of an ideal gas under isothermal condition, the correct option is:
An organic compound contains $80%$ (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is: [Atomic wt. of $C$ is $12$ and of $H$ is $1$]
The following solutions were prepared by dissolving $10g$ of glucose $({C}_{6}{H}_{12}{O}_{6})$ in $250\mathrm{mL}$ of water $({P}_{1}),10g$ of urea $({\mathrm{CH}}_{4}{N}_{2}O)$ in $250\mathrm{mL}$ of water $({P}_{2})$ and $10g$ of sucrose $({C}_{12}{H}_{22}{O}_{11})$ in $250\mathrm{mL}$ of water $({P}_{3}).$ The right option for the decreasing order of osmotic pressure of these solutions is:
The ${\mathrm{pK}}_{b}$ of dimethylamine and ${\mathrm{pK}}_{a}$ of acetic acid are $3.27$and $4.77$ respectively at $T(K).$ The correct option for the $\mathrm{pH}$ of dimethylammonium acetate solution is: