JEE Main Chemistry — Physical Chemistry previous year questions with solutions.
Consider the following half cell reaction $\mathrm{Cr}_2 \mathrm{O}_7^{2-}(\mathrm{aq})+6 \mathrm{e}^{-}+14 \mathrm{H}^{+}(\mathrm{aq})$ $\rightarrow 2 \mathrm{Cr}^{3+}(\mathrm{aq})+7 \mathrm{H}_2 \mathrm{O}(\mathrm{l})$ The reaction was conducted with the ratio of $\frac{\left[\mathrm{Cr}^{3+}\right]^2}{\left[\mathrm{Cr}_2 \mathrm{O}_7^{2-}\right]}=10^{-6}$. The pH value at which the EMF of the half cell will become zero is ________. (nearest integer value) [Given : standard half cell reduction potential $\left.\mathrm{E}_{\mathrm{Cr}_2 \mathrm{O}_7^{2-}, \mathrm{H}^{+} / \mathrm{Cr}^{3+}}^{\mathrm{o}}=1.33 \mathrm{~V}, \frac{2.303 \mathrm{RT}}{\mathrm{~F}}=0.059 \mathrm{~V}\right]$
Xg of benzoic acid on reaction with aq $\mathrm{NaHCO}_3$ released $\mathrm{CO}_2$ that occupied 11.2 L volume at STP. X is _____ g.
$\mathrm{FeO}_4^{2-} \xrightarrow{+2.0 \mathrm{v}} \mathrm{Fe}^{3+} \xrightarrow{0.8 \mathrm{v}} \mathrm{Fe}^{2+} \xrightarrow{-0.5 \mathrm{v}} \mathrm{Fe}^0$ In the above diagram, the standard electrode potentials are given in volts (over the arrow). The value of $\mathrm{E}_{\mathrm{FeO}_4^{2-} / \mathrm{Fe}^{2+}}^{\mathrm{O}}$ is
Consider the ground state of chromium atom $(\mathrm{Z}=24)$. How many electrons are with Azimuthal quantum number $l=1$ and $l=2$ respectively ?
Choose the correct statements. (A) Weight of a substance is the amount of matter present in it. (B) Mass is the force exerted by gravity on an object. (C) Volume is the amount of space occupied by a substance. (D) Temperatures below \(0^{\circ} \mathrm{C}\) are possible in Celsius scale, but in Kelvin scale negative temperature is not possible. (E) Precision refers to the closeness of various measurements for the same quantity. Choose the correct answer from the options given below :
Fortification of food with iron is done using $\mathrm{FeSO}_4 \cdot 7 \mathrm{H}_2 \mathrm{O}$. The mass in grams of the $\mathrm{FeSO}_4 \cdot 7 \mathrm{H}_2 \mathrm{O}$ required to achieve 12 ppm of iron in 150 kg of wheat is ____ (Nearest integer) [Given : Molar mass of $\mathrm{Fe}, \mathrm{S}$ and O respectively are 56,32 and $16 \mathrm{~g} \mathrm{~mol}^{-1}$ ]
According to Bohr's model of hydrogen atom, which of the following statement is incorrect?
Arrange the following in increasing order of solubility product : $\mathrm{Ca}(\mathrm{OH})_2, \mathrm{AgBr}, \mathrm{PbS}, \mathrm{HgS}$
Given below are two statements Statement I : A catalyst cannot alter the equilibrium constant $\left(\mathrm{K}_{\mathrm{c}}\right)$ of the reaction, temperature remaining constant Statement II : A homogenous catalyst can change the equilibrium composition of a system temperature remaining constant In the light of the above statements, choose the correct answer from the options given below
 Consider the above sequence of reactions. 151 g of 2-bromopentane is made to react. Yield of major product P is $80 \%$ whereas Q is $100 \%$. Mass of product Q obtained is ____ g. (Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} \mathrm{H}: 1, \mathrm{C}: 12, \mathrm{O}: 16$, $\mathrm{Br}: 80)$
$\mathrm{O}_2$ gas will be evolved as a product of electrolysis of : (A) an aqueous solution of $\mathrm{AgNO}_3$ using silver electrodes. (B) an aqueous solution of $\mathrm{AgNO}_3$ using platinum electrodes. (C) a dilute solution of $\mathrm{H}_2 \mathrm{SO}_4$ using platinum electrodes. (D) a high concentration solution of $\mathrm{H}_2 \mathrm{SO}_4$ using platinum electrodes. Choose the correct answer from the options given below :
Which of the following happens when $\mathrm{NH}_4 \mathrm{OH}$ is added gradually to the solution containing 1 M $\mathrm{A}^{2+}$ and $1 \mathrm{MB}^{3+}$ ions? Given : $\mathrm{K}_{\mathrm{sp}}\left[\mathrm{A}(\mathrm{OH})_2\right]=9 \times 10^{-10}$ and $\mathrm{K}_{\mathrm{sp}}\left[\mathrm{B}(\mathrm{OH})_3\right]=27 \times 10^{-18}$ at 298 K .
For electron in ' 2 s ' and ' 2 p ' orbitals, the orbital angular momentum values, respectively are :
Let us consider a reversible reaction at temperature, T. In this reaction, both $\Delta \mathrm{H}$ and $\Delta \mathrm{S}$ were observed to have positive values. If the equilibrium temperature is Te , then the reaction becomes spontaneous at :
\(\mathrm{CaCO}_3(\mathrm{~s})+2 \mathrm{HCl}(\mathrm{aq}) \rightarrow \mathrm{CaCl}_2(\mathrm{aq})+\mathrm{CO}_2(\mathrm{~g}) \mathrm{H}_2 \mathrm{O}(\mathrm{l})\) Consider the above reaction, what mass of \(\mathrm{CaCl}_2\) will be formed if 250 mL of 0.76 M HCl reacts with 1000 g of \(\mathrm{CaCO}_3\) ? (Given : Molar mass of \(\mathrm{Ca}, \mathrm{C}, \mathrm{O}, \mathrm{H}\) and Cl are 40, \(12,16,1\) and \(35.5 \mathrm{~g} \mathrm{~mol}^{-1}\), respectively)
Radius of the first excited state of Helium ion is given as : $\mathrm{a}_0 \rightarrow$ radius of first stationary state of hydrogen atom.
If equal volumes of \(\mathrm{AB}_2\) and XY (both are salts) aqueous solutions are mixed, which of the following combination will give a precipitate of \(\mathrm{AY}_2\) at 300 K ? (Given \(\mathrm{K}_{\mathrm{sp}}\) (at 300 K) for \(\mathrm{AY}_2=5.2 \times 10^{-7}\))
Given below are two statements :  In the light of the above statements, choose the correct answer from the options given below :
The molar solubility(s) of zirconium phosphate with molecular formula $\left(\mathrm{Zr}^{4+}\right)_3\left(\mathrm{PO}_4^{3-}\right)_4$ is given by relation :
Given below are two statements : Statement (I) : Molal depression constant $\mathrm{K}_{\mathrm{f}}$ is given by $\frac{M_1 R T_f}{\Delta S_{f u s}}$, where symbols have their usual meaning. Statement (II) : $\mathrm{K}_{\mathrm{f}}$ for benzene is less than the $\mathrm{K}_{\mathrm{f}}$ for water. In the light of the above statements, choose the most appropriate answer from the options given below :
For the reaction $\mathrm{A} \rightarrow \mathrm{B}$ the following graph was obtained. The time required (in seconds) for the concentration of A to reduce to $2.5 \mathrm{~g} \mathrm{~L}^{-1}$ (if the initial concentration of A was $50 \mathrm{~g} \mathrm{~L}^{-1}$) is _______ (Nearest integer) Given : $\log 2=0.3010$ [We can assume in a hypothetical situation that the graph is correct, assuming its first order reaction, in reality the question is wrong.] 
The formation enthalpies, $\Delta \mathrm{H}_{\mathrm{f}} \ominus$ for $\mathrm{H}_{(\mathrm{g})}$ and $\mathrm{O}_{(\mathrm{g})}$ are 220.0 and $250.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$, respectively, at 298.15 K , and $\Delta \mathrm{H}_{\mathrm{f}}{ }^{\ominus}$ for $\mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}$ is $-242.0 \mathrm{~kJ} \mathrm{~mol}^{-1}$ at the same temperature. The average bond enthalpy of the $\mathrm{O}-\mathrm{H}$ bond in water at 298.15 K is __________ $\mathrm{kJ} \mathrm{mol}^{-1}$ (nearest integer).
When a non-volatile solute is added to the solvent, the vapour pressure of the solvent decreases by 10 mm of Hg . The mole fraction of the solute in the solution is 0.2 . What would be the mole fraction of the solvent if decrease in vapour pressure is 20 mm of Hg ?
 A perfect gas $(0.1 \mathrm{~mol})$ having $\overline{\mathrm{C}}_{\mathrm{v}}=1.50 \mathrm{R}$ (independent of temperature) undergoes the above transformation from point 1 to point 4. If each step is reversible, the total work done (w) while going from point 1 to point 4 is $(-)$ ________ J (nearest integer) $\left[\right.$ Given : $\left.\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right]$