JEE Main Chemistry — Physical Chemistry previous year questions with solutions.
$20%$ of acetic acid is dissociated when its $5g$ is added to $500\mathrm{mL}$ of water. The depression in freezing point of such water is $_____\times {10}^{-3}C\circ$. Atomic mass of $C,H$ and $O$ are $12,1$ and $16$ a.m.u. respectively. [Given : Molal depression constant and density of water are $1.86K\mathrm{kg}{\mathrm{mol}}^{-1}$ and $1g{\mathrm{cm}}^{-3}$ respectively.
If the degree of dissociation of aqueous solution of weak monobasic acid is determined to be $0.3$, then the observed freezing point will be _____ $%$ higher than the expected/theoretical freezing point. (Nearest integer).
$28.0$ L of ${\mathrm{CO}}_{2}$ is produced on complete combustion of $16.8L$ gaseous mixture of ethene and methane at $25^{\circ}C$ and $1$ atm. Heat evolved during the combustion process is $\mathrm{kJ}$ Given$:{\Delta H}_{C}({\mathrm{CH}}_{4})=-900\mathrm{kJ}{\mathrm{mol}}^{-1}$ ${\Delta H}_{C}({C}_{2}{H}_{4})=-1400\mathrm{kJ}{\mathrm{mol}}^{-1}$.
Arrange the following orbitals in decreasing order of energy. A. $n=3,l=0,m=0$ B. $n=4,l=0,m=0$ C. $n=3,l=1,m=0$ D. $n=3,l=2,m=1$ The correct option for the order is:
When a hydrocarbon $A$ undergoes complete combustion it requires $11$ equivalents of oxygen and produces $4$ equivalents of water. What is the molecular formula of $A$?
The number of correct statements from the following is ___________ (A) Conductivity always decreases with decrease in concentration for both strong and weak electrolytes. (B) The number of ions per unit volume that carry current in a solution increases on dilution. (C) Molar conductivity increases with decrease in concentration. (D) The variation in molar conductivity is different for strong and weak electrolytes. (E) For weak electrolytes, the change in molar conductivity with dilution is due to decrease in degree of dissociation.
In the depression of freezing point experiment A. Vapour pressure of the solution is less than that of pure solvent B. Vapour pressure of the solution is more than that of pure solvent C. Only solute molecules solidify at the freezing point D. Only solvent molecules solidify at the freezing point
The standard electrode potential (${M}^{3+}/{M}^{2+}$) for $V,\mathrm{Cr},\mathrm{Mn}$ & $\mathrm{Co}$ are $-0.26V,-0.41V,+1.57V$ and $+1.97V$, respectively. The metal ions which can liberate ${H}_{2}$ from a dilute acid are
A student has studied the decomposition of a gas $A{B}_{3}$ at $25^{\circ}C$. He obtained the following data <table class="pyq-table"><tbody><tr><td>$p(mmHg)$</td><td>$50$</td><td>$100$</td><td>$200$</td><td>$400$</td></tr><tr><td>Relative ${t}_{\frac{1}{2}}(s)$</td><td>$4$</td><td>$2$</td><td>$1$</td><td>$0.5$</td></tr></tbody></table>The order of the reaction is
Which of the following options are correct for the reaction? $2{[\mathrm{Au}(\mathrm{CN}{)}_{2}]}^{-}(\mathrm{aq})+\mathrm{Zn}(s)\rightarrow 2\mathrm{Au}(s)+{[\mathrm{Zn}(\mathrm{CN}{)}_{4}]}^{2-}(\mathrm{aq})$ A. Redox reaction B. Displacement reaction C. Decomposition reaction D. Combination reaction Choose the correct answer from the options given below:
On complete combustion, $0.492g$ of an organic compound gave $0.792g$ of ${\mathrm{CO}}_{2}$. The $%$ of carbon in the organic compound is (Nearest integer)
In alkaline medium, the reduction of permanganate anion involves a gain of ____________ electrons.
$1g$ of a carbonate $({M}_{2}{\mathrm{CO}}_{3})$ on treatment with excess $\mathrm{HCl}$ produces $0.01\mathrm{mol}$ of ${\mathrm{CO}}_{2}$. The molar mass of ${M}_{2}{\mathrm{CO}}_{3}$ is ${\mathrm{gmol}}^{-1}$. (Nearest integer)
Which of the following statement(s) is/are correct? (A) The $\mathrm{pH}$ of $1\times {10}^{–8}M\mathrm{HCl}$ solution is $8$. (B) The conjugate base of ${H}_{2}{\mathrm{PO}}^{4-}$ is ${\mathrm{HPO}}_{4}^{2-}$. (C) ${K}_{w}$ increases with increase in temperature. (D) When a solution of a weak monoprotic acid is titrated against a strong base at half neutralisation point, $\mathrm{pH}=\frac{1}{2}{\mathrm{pK}}_{a}$. Choose the correct answer from the options given below:
The density of a monobasic strong acid (Molar mass $24.2g\mathrm{mol})$ is $1.21\mathrm{kg}L$. The volume of its solution required for the complete neutralization of $25\mathrm{mL}$ of $0.24M\mathrm{NaOH}$ is ${10}^{-2}\mathrm{mL}$ (Nearest integer)
$600\mathrm{mL}$ of $0.01M\mathrm{HCl}$ is mixed with $400\mathrm{mL}$ of $0.01M{H}_{2}{\mathrm{SO}}_{4}$. The $\mathrm{pH}$ of the mixture is _____$\times {10}^{-2}$. (Nearest integer) [Given $\mathrm{log}2=0.30,\mathrm{log}3=0.48,\mathrm{log}5=0.69,\mathrm{log}7=0.84,\mathrm{log}11=1.04$]
Consider the following pairs of solution which will be isotonic at the same temperature. The number of pairs of solutions is/ are _____ A. $1M\mathrm{aq}.\mathrm{NaCl}$ and $2M\mathrm{aq}.$ urea B. $1M\mathrm{aq}.{\mathrm{CaCl}}_{2}$ and $1.5M\mathrm{aq}.\mathrm{KCl}$ C. $1.5M\mathrm{aq}.{\mathrm{AlCl}}_{3}$ and $2M\mathrm{aq}.{\mathrm{Na}}_{2}{\mathrm{SO}}_{4}$ D. $2.5M\mathrm{aq}.\mathrm{KCl}$ and $1M\mathrm{aq}.{\mathrm{Al}}_{2}({\mathrm{SO}}_{4}{)}_{3}$
Assume that the radius of the first Bohr orbit of hydrogen atom is $0.6Å$. The radius of the third Bohr orbit of ${\mathrm{He}}^{+}$ is _____ picometer. (Nearest Integer)
The molality of a $10%(v/V)$ solution of di-bromine solution in ${\mathrm{CCl}}_{4}$ (carbon tetrachloride) is $x$ '. $x=$ $_____\times {10}^{-2}M$. (Nearest integer) [Given : molar mass of ${\mathrm{Br}}_{2}=160g{\mathrm{mol}}^{-1}$ atomic mass of $C=12g{\mathrm{mol}}^{-1}$ atomic mass of $\mathrm{Cl}=35.5g{\mathrm{mol}}^{-1}$ density of dibromine $=3.2g{\mathrm{cm}}^{-3}$ density of ${\mathrm{CCl}}_{4}=1.6g{\mathrm{cm}}^{-3}]$
A solution is prepared by adding $2g$ of $''X''$ to $1$ mole of water. Mass percent of $''X''$in solution is
At $27^{\circ}C$, a solution containing $2.5g$ of solute in $250.0\mathrm{mL}$ of solution exerts an osmotic pressure of $400\mathrm{Pa}$. The molar mass of the solute is g ${\mathrm{mol}}^{-1}$ (Nearest integer) (Given : $R=0.083L$ bar $-1{\mathrm{mol}}^{-1}$ )
An analyst wants to convert $1L\mathrm{HCl}$ of $\mathrm{pH}=1$ to a solution of $\mathrm{HCl}$ of $\mathrm{pH}=2$. The volume of water needed to do this dilution is _____ $\mathrm{mL}$. (Nearest integer)
At $298K$ ${N}_{2}(g)+3{H}_{2}(g)\rightleftharpoons 2{\mathrm{NH}}_{3}(g),{K}_{1}=4\times {10}^{5}$ ${N}_{2}(g)+{O}_{2}(g)\rightleftharpoons 2\mathrm{NO}(g),{K}_{2}=1.6\times {10}^{12}$ ${H}_{2}(g)+\frac{1}{2}{O}_{2}(g)\rightleftharpoons {H}_{2}O(g),{K}_{3}=1.0\times {10}^{-13}$ Based on above equilibria, the equilibrium constant of the reaction, $2{\mathrm{NH}}_{3}(g)+\frac{5}{2}{O}_{2}(g)\rightleftharpoons 2\mathrm{NO}(g)+3{H}_{2}O(g)$ is _____ $\times {10}^{-33}$ (Nearest integer)
Which one of the following statements is correct for electrolysis of brine solution?