JEE Main Chemistry — Physical Chemistry previous year questions with solutions.
Experimentally it was found that a metal oxide has formula ${M}_{0.98}O$. Metal M, is present as ${M}^{2+}$ and ${M}^{3+}$ in its oxide. Fraction of the metal which exists as ${M}^{3+}$ would be:
Which one of the following arrangements represents the correct order of solubilities of sparingly soluble salts $\mathrm{Hg}_2 \mathrm{Cl}_2, \mathrm{Cr}_2\left(\mathrm{SO}_4\right)_3$, $\mathrm{BaSO}_4$ and $\mathrm{CrCl}_3$ respectively?
Number of atoms in the following samples of substances is largest in:
Given : $\mathrm{XNa}_2 \mathrm{HAsO}_3+\mathrm{YNaBrO}_3+\mathrm{ZHCl} \rightarrow \mathrm{NaBr}+\mathrm{H}_3 \mathrm{AsO}_4+\mathrm{NaCl}$ The values of $\mathrm{X}, \mathrm{Y}$ and $\mathrm{Z}$ in the above redox reaction are respectively :
$10 \mathrm{~mL}$ of $2(\mathrm{M}) \mathrm{~NaOH}$ solution is added to $200 \mathrm{~mL}$ of $0.5$ $\mathrm{(M)}$ of $\mathrm{NaOH}$ solution. What is the final concentration ?
The Gibbs energy for the decomposition of $\mathrm{Al}_2 \mathrm{O}_3$ at $500 \mathrm{~C}$ is as follows : $\frac{2}{3} \mathrm{Al}_2 \mathrm{O}_3 \rightarrow \frac{4}{3} \mathrm{Al}+\mathrm{O}_2, \Delta_r G=+940 \mathrm{~kJ} \mathrm{~mol}^{-1}$ The potential difference needed for the electrolytic reduction of aluminium oxide at $500^{\circ} \mathrm{C}$ should be at least :
A solution of copper sulphate $\left(\mathrm{CuSO}_4\right)$ is electrolysed for $10$ minutes with a current of $1.5$ amperes. The mass of copper deposited at the cathode (at. mass of $\mathrm{Cu}=63 \mathrm{u}$ ) is :
Four successive members of the first row of transition elements are listed below with atomic numbers. Which one of them is expected to have the highest ${\text{E}}_{{\text{M}}^{3+}/{\text{M}}^{2+}}^{o}$ value?
The de Broglie wavelength of a car of mass 1000 $\mathrm{kg}$ and velocity $36 \mathrm{~km} / \mathrm{hr}$ is :
The molarity of a solution obtained by mixing $750\mathrm{mL}$ of $0.5(M)\mathrm{HCl}$ with $250\mathrm{mL}$ of $2(M)\mathrm{HCl}$ will be
Given that: (i) $\Delta_{\mathrm{f}} \mathrm{H}^{\circ}$ of $\mathrm{N}_2 \mathrm{O}$ is $82 \mathrm{~kJ} \mathrm{~mol}^{-1}$ (ii) Bond energies of $\mathrm{N} \equiv \mathrm{N}, \mathrm{N}=\mathrm{N}, \mathrm{O}=\mathrm{O}$ and $\mathrm{N}=\mathrm{O}$ are $946,418,498$ and $607 \mathrm{~kJ} \mathrm{~mol}^{-1}$ respectively, The resonance energy of $\mathrm{N}_2 \mathrm{O}$ is :
Given Reaction Energy Change $\begin{array}{ll} & \text { (in kJ) } \\ \mathrm{Li}(\mathrm{s}) \rightarrow \mathrm{Li}(\mathrm{g}) & 161 \\ \mathrm{Li}(\mathrm{g}) \rightarrow \mathrm{Li}^{+}(\mathrm{g}) & 520 \\ \frac{1}{2} \mathrm{~F}_2(\mathrm{~g}) \rightarrow \mathrm{F}(\mathrm{g}) & 77 \\ \mathrm{~F}(\mathrm{~g})+\mathrm{e}^{-} \rightarrow \mathrm{F}^{-}(\mathrm{g}) & \begin{array}{l}\text { (Electron gain } \\ \text { enthalpy) }\end{array} \\ \mathrm{Li}^{+}(\mathrm{g})+\mathrm{F}^{-}(\mathrm{g}) \rightarrow \mathrm{LiF}(\mathrm{s}) & -1047 \\ \mathrm{Li}(\mathrm{s})+\frac{1}{2} \mathrm{~F}_2(\mathrm{~g}) \rightarrow \mathrm{LiF}(\mathrm{s}) & -617\end{array}$ Based on data provided, the value of electron gain enthalpy of fluorine would be :
Given : $$ \begin{gathered} \mathrm{E}_{\frac{1}{2} \mathrm{Cl}_2 / \mathrm{Cl}^{-}}^{\mathrm{o}}=1.36 \mathrm{~V}, \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{\mathrm{o}}=-0.74 \mathrm{~V} \\ \mathrm{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-} / \mathrm{Cr}^{3+}}^{\mathrm{o}}=1.33 \mathrm{~V}, \mathrm{E}_{\mathrm{MnO}_4^{-} / \mathrm{Mn}^{2+}}^{\mathrm{o}}=1.51 \mathrm{~V} \end{gathered} $$ The correct order of reducing power of the species $\left(\mathrm{Cr}, \mathrm{Cr}^{3+}, \mathrm{Mn}^{2+}\right.$ and $\left.\mathrm{Cl}^{-}\right)$will be:
The rate of a reaction doubles when its temperature changes from $300K\mathrm{to}310K$. Activation energy of such a reaction will be: $(\text{R}={\text{8.314 JK}}^{-1}{mol}^{-1}\mathrm{and}log 2=\text{0.301})$
$\mathrm{NaOH}$ is a strong base. What will be $\mathrm{pH}$ of $5.0 \times 10^{-2} \mathrm{M} \mathrm{NaOH}$ solution ? $(\log 2=0.3)$
What would be the $\mathrm{pH}$ of a solution obtained by mixing $5 \mathrm{~g}$ of acetic acid and $7.5 \mathrm{~g}$ of sodium acetate and making the volume equal to $500 \mathrm{~mL}$ ? $\left(\mathrm{K}_{\mathrm{a}}=1.75 \times 10^{-5}, \mathrm{pK}_{\mathrm{a}}=4.76\right)$
A gaseous hydrocarbon on combustion gives $0.72g$ of water and $3.08g$ ${\mathrm{CO}}_{2}$. What is the empirical formula of the hydrocarbon?
$6$ litres of an alkene require $27$ litres of oxygen at constant temperature and pressure for complete combustion. The alkene is :
What is the $\mathrm{pH}$ of a $10^{-4} \mathrm{M} \mathrm{OH}^{-}$solution at $330 \mathrm{~K}$, if $\mathrm{K}_{\mathrm{w}}$ at $330 \mathrm{~K}$ is $10^{-13.6}$ ?
Consider the following reaction: $x {\mathrm{MnO}}_{4}^{-}+y {C}_{2}{O}_{4}^{2-}+{\mathrm{zH}}^{+}\longrightarrow x {\mathrm{Mn}}^{2+}+2y {\mathrm{CO}}_{2}+\frac{z}{2}{H}_{2}O$ The values of x, y and z in the reaction are, respectively:
$12 \mathrm{~g}$ of a nonvolatile solute dissolved in $108 \mathrm{~g}$ of water produces the relative lowering of vapour pressure of $0.1$. The molecular mass of the solute is :
Electrode potentials $\left(\mathrm{E}^{\circ}\right)$ are given below : $\begin{aligned} & \mathrm{Cu}^{+} / \mathrm{Cu}=+0.52 \mathrm{~V} ,\\ & \mathrm{Fe}^{3+} / \mathrm{Fe}^{2+}=+0.77 \mathrm{~V}, \\ & \frac{1}{2} \mathrm{I}_2(\mathrm{~s}) / \mathrm{I}^{-}=+0.54 \mathrm{~V}, \\ & \mathrm{Ag}^{+} / \mathrm{Ag}=+0.88 \mathrm{~V}. \end{aligned}$ Based on the above potentials, strongest oxidizing agent will be :
Given (A) $\mathrm{n}=5, \mathrm{~m}_{\ell}=+1$ (B) $\mathrm{n}=2, \ell=1, \mathrm{~m}_{\ell}=-1, \mathrm{~m}_{\mathrm{s}}=-\mathrm{l} / 2$ The maximum number of electron(s) in an atom that can have the quantum numbers as given in (A) and (B) are respectively:
The ratio $\frac{K_p}{K_c}$ for the reaction $\mathrm{CO}(g)+\frac{1}{2} O_2(g) \rightleftharpoons C O_2(g)$ is: