Mole Concept & Stoichiometry · JEE Main previous year questions

An organic compound $(\mathrm{P})$ on treatment with aqueous ammonia under hot condition forms compound $(\mathrm{Q})$ which on heating with $\mathrm{B}{\mathrm{r}}_2$ and KOH forms compound $(\mathrm{R})$ having molecular formula ${\mathrm{C}}_6{\mathrm{H}}_7\mathrm{N}$. Names of P, Q and R respectively are.

1. A.Toluic acid, methylbenzamide, 2-methylaniline
2. B.Benzoic acid, benzamide, aniline
3. C.Benzoic acid, 4-methylbenzamide, 4-methylaniline
4. D.Phenylethanoic acid, phenylethanamide, benzamine

1. A.
2. B.
3. C.
4. D.

An organic compound " P " of molecular formula ${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_3$ gives positive Iodoform test but negative Tollen's test. When " P " is treated with dilute acid, it produces " Q ". " Q " gives positive Tollen's test and also iodoform test. The structure of " P " is :

1. A.$\mathrm{H}-\mathrm{CO}-\mathrm{C}{\mathrm{H}}_2-\mathrm{C}{\mathrm{H}}_2-\mathrm{CH}(\mathrm{OC}{\mathrm{H}}_3)-\mathrm{OC}{\mathrm{H}}_3$
2. B.$\mathrm{C}{\mathrm{H}}_3-\mathrm{CO}-\mathrm{CH}(\mathrm{OC}{\mathrm{H}}_3)-\mathrm{C}{\mathrm{H}}_2(\mathrm{OC}{\mathrm{H}}_3)$
3. C.$\mathrm{C}{\mathrm{H}}_3-\mathrm{CO}-\mathrm{C}{\mathrm{H}}_2-\mathrm{CH}(\mathrm{OC}{\mathrm{H}}_3)-\mathrm{OC}{\mathrm{H}}_3$
4. D.$\mathrm{C}{\mathrm{H}}_3-\mathrm{CO}-\mathrm{C}(\mathrm{OC}{\mathrm{H}}_3{)}_2-\mathrm{C}{\mathrm{H}}_3$

Use the following data : $$\begin{array}{ccc}\text{Substance}& \frac{{\Delta }_f{\mathrm{H}}^{\ominus }(500\mathrm{K})}{\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}}& \frac{{\mathrm{S}}^{\ominus }(500\mathrm{K})}{\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}}\\ \mathrm{AB}(\mathrm{g})& 32& 222\\ {\mathrm{A}}_2(\mathrm{g})& 6& 146\\ {\mathrm{B}}_2(\mathrm{g})& x& 280\end{array}$$ One mole each of ${\mathrm{A}}_2(\mathrm{g})$ and ${\mathrm{B}}_2(\mathrm{g})$ are taken in a 1 L closed flask and allowed to establish the equilibrium at 500 K . ${\mathrm{A}}_2(\mathrm{g})+{\mathrm{B}}_2(\mathrm{g})\rightleftharpoons 2AB(\mathrm{g})$ The value of $x$ $\left(\mathrm{in}\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}\right)$ is ____. (Nearest integer) (Given : $\log \mathrm{K}=2.2\mathrm{R}=8.3\mathrm{J}{\mathrm{K}}^{-1}\mathrm{mo}{\mathrm{l}}^{-1}$)

20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is ____ M. (Nearest Integer value) $(\text{Given : }\mathrm{Na}=23,\mathrm{I}=127,\mathrm{Ag}=108,\mathrm{N}=14,\mathrm{O}=16\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1})$

An organic compound (X) with molecular formula ${\mathrm{C}}_3{\mathrm{H}}_6\mathrm{O}$ is not readily oxidised. On reduction it gives ${\mathrm{C}}_3{\mathrm{H}}_8\mathrm{O}(\mathrm{Y})$ which reacts with HBr to give a bromide (Z) which is converted to Grignard reagent. This Grignard reagent on reaction with (X) followed by hydrolysis gives 2,3-dimethylbutan-2-ol. Compounds (X), (Y) and (Z) respectively are:

1. A.$\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{CHO},\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{OH},\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{Br}$
2. B.$\mathrm{C}{\mathrm{H}}_3\mathrm{COC}{\mathrm{H}}_3,\mathrm{C}{\mathrm{H}}_3\mathrm{CH}(\mathrm{OH})\mathrm{C}{\mathrm{H}}_3,\mathrm{C}{\mathrm{H}}_3\mathrm{CH}(\mathrm{Br})\mathrm{C}{\mathrm{H}}_3$
3. C.$\mathrm{C}{\mathrm{H}}_3\mathrm{COC}{\mathrm{H}}_3,\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2\mathrm{OH},\mathrm{C}{\mathrm{H}}_3\mathrm{CH}(\mathrm{Br})\mathrm{C}{\mathrm{H}}_3$
4. D.$\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2\mathrm{CHO},\mathrm{C}{\mathrm{H}}_3\mathrm{CH}=\mathrm{C}{\mathrm{H}}_2,\mathrm{C}{\mathrm{H}}_3\mathrm{CH}(\mathrm{Br})\mathrm{C}{\mathrm{H}}_3$

Sea water, which can be considered as a 6 molar ($6\mathrm{M}$) solution of $\mathrm{NaCl}$, has a density of $2{\mathrm{g}\mathrm{mL}}^{-1}$. The concentration of dissolved oxygen (${\mathrm{O}}_2$) in sea water is $5.8\mathrm{ppm}$. Then the concentration of dissolved oxygen (${\mathrm{O}}_2$) in sea water, in terms of molality, is $x\times 10^{-4}\mathrm{m}$. $x=\underline{}$. (Nearest integer) Given: Molar mass of $\mathrm{NaCl}$ is $58.5{\mathrm{g}\mathrm{mol}}^{-1}$ Molar mass of ${\mathrm{O}}_2$ is $32{\mathrm{g}\mathrm{mol}}^{-1}$

10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is :

1. A.0.2 M NaCl solution
2. B.20 M HCl solution
3. C.Neutral solution
4. D.10 M HCl solution

The total number of structural isomers possible for the substituted benzene derivatives with the molecular formula ${\mathrm{C}}_9{\mathrm{H}}_{12}$ is__________.

A solution is made by mixing one mole of volatile liquid $A$ with 3 moles of volatile liquid $B$. The vapour pressure of pure A is $200\text{ mm Hg}$ and that of the solution is $500\text{ mm Hg}$. The vapour pressure of pure B and the least volatile component of the solution, respectively, are:

1. A.1400 mm Hg, A
2. B.1400 mm Hg, B
3. C.600 mm Hg, A
4. D.600 mm Hg, B

On complete combustion $1.0\text{ g}$ of an organic compound $(\mathrm{X})$ gave $1.46\text{ g}$ of ${\mathrm{CO}}_2$ and $0.567\text{ g}$ of ${\mathrm{H}}_2\mathrm{O}$. The empirical formula mass of compound $(\mathrm{X})$ is _________ g. (Given molar mass in ${\text{gmol}}^{-1}\mathrm{C}:12,\mathrm{H}:1,\mathrm{O}:16$ )

1. A.60
2. B.45
3. C.30
4. D.15

1. A.
2. B.
3. C.
4. D.

$0.1\mathrm{M}$ solution of $\mathrm{KI}$ reacts with excess of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ and $\mathrm{KI}{\mathrm{O}}_3$ solutions. According to equation $$5{\mathrm{I}}^{-}+\mathrm{I}{\mathrm{O}}_3^{-}+6{\mathrm{H}}^{+}\to 3{\mathrm{I}}_2+3{\mathrm{H}}_2\mathrm{O}$$ Identify the correct statements : (A) $200\mathrm{mL}$ of $\mathrm{KI}$ solution reacts with $0.004\mathrm{mol}$ of $\mathrm{KI}{\mathrm{O}}_3$ (B) $200\mathrm{mL}$ of $\mathrm{KI}$ solution reacts with $0.006\mathrm{mol}$ of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ (C) $0.5\mathrm{L}$ of $\mathrm{KI}$ solution produced $0.005\mathrm{mol}$ of ${\mathrm{I}}_2$ (D) Equivalent weight of $\mathrm{KI}{\mathrm{O}}_3$ is equal to $(\frac{\text{Molecular weight}}{5})$ Choose the correct answer from the options given below :

1. A.(C) and (D) only
2. B.(A) and (B) only
3. C.(B) and (C) only
4. D.(A) and (D) only

The molarity of a 70% (mass/mass) aqueous solution of a monobasic acid (X) is ____ $\times 10^{-1}\mathrm{M}$ (Nearest integer) [Given: Density of aqueous solution of (X) is $1.25\mathrm{g}\mathrm{m}{\mathrm{L}}^{-1}$ Molar mass of the acid is $70\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ ]

Quantitative analysis of an organic compound (X) shows following % composition. C : 14.5% Cl : 64.46% H: 1.8 % Empirical formula mass of the compound (X) is ____ $\times 10^{-1}$ (Given molar mass in $\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$ of C : 12, H : 1, O : 16, Cl : 35.5)

One mole of the octahedral complex compound $\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_5\mathrm{C}{\mathrm{l}}_3$ gives 3 moles of ions on dissolution in water. One mole of the same complex reacts with excess of $\mathrm{AgN}{\mathrm{O}}_3$ solution to yield two moles of $\mathrm{AgC}{\mathrm{l}}_{(\mathrm{s})}$. The structure of the complex is:

1. A.$[\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_5\mathrm{Cl}]\mathrm{C}{\mathrm{l}}_2$
2. B.$[\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_4\mathrm{Cl}]\cdot \mathrm{C}{\mathrm{l}}_2\cdot \mathrm{N}{\mathrm{H}}_3$
3. C.$[\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_3\mathrm{C}{\mathrm{l}}_3]\cdot 2N{\mathrm{H}}_3$
4. D.$[\mathrm{Co}(\mathrm{N}{\mathrm{H}}_3{)}_4\mathrm{C}{\mathrm{l}}_2]\cdot \mathrm{Cl}\cdot \mathrm{N}{\mathrm{H}}_3$

The elemental composition of a compound is $54.2\%\mathrm{C},9.2\%\mathrm{H}$ and $36.6\%\mathrm{O}$. If the molar mass of the compound is $132{\text{ g mol}}^{-1}$, the molecular formula of the compound is : [Given : The relative atomic mass of $\mathrm{C}:\mathrm{H}:\mathrm{O}=12:1:16$]

1. A.${\mathrm{C}}_4{\mathrm{H}}_8{\mathrm{O}}_2$
2. B.${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6$
3. C.${\mathrm{C}}_4{\mathrm{H}}_9{\mathrm{O}}_3$
4. D.${\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_3$

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 ?

1. A.0.2
2. B.0.4
3. C.0.8
4. D.0.6

Consider a binary solution of two volatile liquid components 1 and 2. $x_1$ and $y_1$ are the mole fractions of component 1 in liquid and vapour phase, respectively. The slope and intercept of the linear plot of $\frac{1}{x_1}$ vs $\frac{1}{y_1}$ are given respectively as :

1. A.$\frac{{\mathrm{P}}_1^0}{{\mathrm{P}}_2^0},\frac{{\mathrm{P}}_1^0-{\mathrm{P}}_2^0}{{\mathrm{P}}_2^0}$
2. B.$\frac{{\mathrm{P}}_2^0}{{\mathrm{P}}_1^0},\frac{{\mathrm{P}}_2^0-{\mathrm{P}}_1^0}{{\mathrm{P}}_1^0}$
3. C.$\frac{{\mathrm{P}}_2^0}{{\mathrm{P}}_1^0},\frac{{\mathrm{P}}_1^0-{\mathrm{P}}_2^0}{{\mathrm{P}}_1^0}$
4. D.$\frac{{\mathrm{P}}_1^0}{{\mathrm{P}}_2^0},\frac{{\mathrm{P}}_2^0-{\mathrm{P}}_1^0}{{\mathrm{P}}_2^0}$

$0.01\mathrm{mole}$ of an organic compound $(X)$ containing $10\%$ hydrogen, on complete combustion produced $0.9\mathrm{g}{\mathrm{H}}_2\mathrm{O}$. Molar mass of $(X)$ is ____ $\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$.

A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with $\mathrm{KMn}{\mathrm{O}}_4\mid {\mathrm{H}}^{+}$ gives $$\mathrm{C}{\mathrm{H}}_3-\underset{\underset{\mathrm{O}}{\Vert }}{\mathrm{C}}-\mathrm{C}{\mathrm{H}}_3,\mathrm{C}{\mathrm{H}}_3-\underset{\underset{\mathrm{O}}{\Vert }}{\mathrm{C}}-\mathrm{OH}\text{ and }\mathrm{C}{\mathrm{H}}_3-\underset{\underset{\mathrm{O}}{\Vert }}{\mathrm{C}}-\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_2-\underset{\underset{\mathrm{O}}{\Vert }}{\mathrm{C}}-OH.$$ The total number of $\sigma$ bonds present in the compound ' $X$ ' is ____.

Given below are two statements : Statement I : One mole of propyne reacts with excess of sodium to liberate half a mole of ${\mathrm{H}}_2$ gas. Statement II : Four $\mathrm{g}$ of propyne reacts with ${\mathrm{NaNH}}_2$ to liberate ${\mathrm{NH}}_3$ gas which occupies $224\text{ mL}$ at STP. In the light of the above statements, choose the most appropriate answer from the options given below :

1. A.Both Statement I and Statement II are incorrect
2. B.Statement I is incorrect but Statement II is correct
3. C.Both Statement I and Statement II are correct
4. D.Statement I is correct but Statement II is incorrect

Identify the incorrect statements regarding primary standard of titrimetric analysis. (A) It should be purely available in dry form. (B) It should not undergo chemical change in air. (C) It should be hygroscopic and should react with another chemical instantaneously and stoichiometrically. (D) It should be readily soluble in water. (E) $\mathrm{KMn}{\mathrm{O}}_4$ & $\mathrm{NaOH}$ can be used as primary standard. Choose the correct answer from the options given below :

1. A.(C) and (E) only
2. B.(A) and (B) only
3. C.(B) and (E) only
4. D.(C) and (D) only

Molarity $(\mathrm{M})$ of an aqueous solution containing $x\mathrm{g}$ of anhyd. $\mathrm{CuS}{\mathrm{O}}_4$ in $500\mathrm{mL}$ solution at $32^{\circ }\mathrm{C}$ is $2\times 10^{-1}\mathrm{M}$. Its molality will be ____ $\times 10^{-3}\mathrm{m}$. (nearest integer). [Given density of the solution $=1.25g/mL$]

A solution is prepared by adding $1\text{ mole}$ ethyl alcohol in $9\text{ mole}$ water. The mass percent of solute in the solution is ______ (Integer answer) (Given : Molar mass in ${\mathrm{g}\mathrm{mol}}^{-1}$ Ethyl alcohol : $46$ water : $18$)