JEE Main Chemistry — Physical Chemistry previous year questions with solutions.
The highest electrical conductivity of the following aqueous solutions is of
Calomel $\left(\mathrm{Hg}_2 \mathrm{Cl}_2\right)$ on reaction with ammonium hydroxide gives
If $\alpha$ is the degree of dissociation of $\mathrm{Na}_2 \mathrm{SO}_4$, the vant Hoff's factor (i) used for calculating the molecular mass is
If the bond dissociation energies of $X Y, X_2$ and $Y_2$ (all diatomic molecules) are in the ratio of 1:1:0.5 and $\Delta_t \mathrm{H}$ for the formation of $X Y$ is $-200 \mathrm{~kJ} \mathrm{~mole}^{-1}$. The bond dissociation energy of $\mathrm{X}_2$ will be
An organic compound having molecular mass 60 is found to contain $\mathrm{C}=20 \%, \mathrm{H}=$ $6.67 \%$ and $\mathrm{N}=46.67 \%$ while rest is oxygen. On heating it gives $\mathrm{NH}_3$ alongwith a solid residue. The solid residue give violet colour with alkaline copper sulphate solution. The compound is
Hydrogen ion concentration in mol / L in a solution of pH = 5.4 will be
An amount of solid $\mathrm{NH}_4 \mathrm{HS}$ is placed in a flask already containing ammonia gas at a certain temperature and $0.50 \mathrm{~atm}$. Pressure. Ammonium hydrogen sulphide decomposes to yield $\mathrm{NH}_3$ and $\mathrm{H}_2 \mathrm{~S}$ gases in the flask. When the decomposition reaction reaches equilibrium, the total pressure in the flask rises to $0.84 \mathrm{~atm}$. The equilibrium constant for $\mathrm{NH}_4 \mathrm{HS}$ decomposition at this temperature is
$\mathrm{t}_{1 / 4}$ can be taken as the time taken for the concentration of a reactant to drop to $\frac{3}{4}$ of its initial value. If the rate constant for a first order reaction is $\mathrm{K}$, the $\mathrm{t}_{1 / 4}$ can be written as
For a spontaneous reaction the $\Delta \mathrm{G}$, equilibrium constant $(\mathrm{K})$ and $\mathrm{E}_{\mathrm{cell}}^{\circ}$ will be respectively
Consider an endothermic reaction, $X \longrightarrow Y$ with the activation energies $E_b$ and $E_f$ for the backward and forward reactions, respectively. In general
Aluminium oxide may be electrolysed at $1000^{\circ} \mathrm{C}$ to furnish aluminium metal (Atomic mass $=27$ amu; 1 Faraday $=96,500$ Coulombs). The cathode reaction is $\mathrm{Al}^{3+}+3 \mathrm{e}^{-} \longrightarrow \mathrm{Al}^{\circ}$ To prepare $5.12 \mathrm{~kg}$ of aluminium metal by this method would require
For the reaction $$ \begin{aligned} & 2 \mathrm{NO}_{2(\mathrm{~g})} \rightleftharpoons 2 \mathrm{NO}_{(\mathrm{g})}+\mathrm{O}_{2(\mathrm{~g})} \text {, } \\ & \left(\mathrm{K}_{\mathrm{c}}=1.8 \times 10^{-6} \text {at } 184 \mathrm{C}\right) \\ & (\mathrm{R}=0.0831 \mathrm{~kJ} /(\mathrm{mol} . \mathrm{K}) \end{aligned} $$ When $\mathrm{K}_{\mathrm{p}}$ and $\mathrm{K}_{\mathrm{c}}$ are compared at $184^{\circ} \mathrm{C}$, it is found that
The half - life of a radioisotope is four hours. If the initial mass of the isotope was $200 \mathrm{~g}$, the mass remaining after 24 hours undecayed is
The enthalpies of combustion of carbon and carbon monoxide are $-393.5$ and $-283 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively. The enthalpy of formation of carbon monoxide per mole is
In a cell that utilises the reaction $\mathrm{Zn}(\mathrm{s})+2 \mathrm{H}^{+}(\mathrm{aq}) \longrightarrow \mathrm{Zn}^{2+}(\mathrm{aq})+\mathrm{H}_2(\mathrm{~g})$ addition of $\mathrm{H}_2 \mathrm{SO}_4$ to cathode compartment, will
Which one the following sets of ions represents the collection of isoelectronic species?
Which of the following sets of quantum numbers is correct for an electron in $4 \mathrm{f}$ orbital?
The limiting molar conductivities $\Lambda^{\circ}$ for $\mathrm{NaCl}, \mathrm{KBr}$ and $\mathrm{KCl}$ are 126,152 and $150 \mathrm{~S} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ respectively. The $\Lambda^{\circ}$ for $\mathrm{NaBr}$ is
Consider the ground state of $\mathrm{Cr}$ atom $(Z=24)$. The number of electrons with the azimuthal quantum numbers $\mathrm{I}=1$ and 2 are respectively
The standard e.m.f of a cell, involving one electron change is found to be $0.591 \mathrm{~V}$ at $25^{\circ} \mathrm{C}$. The equilibrium constant of the reaction is $\left(\mathrm{F}=96,500 \mathrm{C} \mathrm{mol}^{-1}: \mathrm{R}=8.314 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)$
The molar solubility product is $\mathrm{K}_{\mathrm{sp}}$. ' $\mathrm{s}$ ' is given in terms of $\mathrm{K}_{\mathrm{sp}}$ by the relation
Among the properties (a) reducing (b) oxidising (c) complexing, the set of properties shown by $\mathrm{CN}^{-}$ion towards metal species is
Excess of $\mathrm{KI}$ reacts with $\mathrm{CuSO}_4$ solution and then $\mathrm{Na}_2 \mathrm{~S}_2 \mathrm{O}_3$ solution is added to it. Which of the statements is incorrect for this reaction?
The $\mathrm{E}_{\mathrm{M}^{+3} / \mathrm{M}^{2+}}^{\circ}$ values for $\mathrm{Cr}, \mathrm{Mn}, \mathrm{Fe}$ and Co are $-0.41,+1.57,+0.77$ and $+1.97 \mathrm{~V}$ respectively. For which one of these metals the change in oxidation state form $+2$ to $+3$ is easiest?