Mole Concept & Stoichiometry · JEE Main previous year questions

$4.5\text{ moles}$ each of hydrogen and iodine is heated in a sealed ten litre vessel. At equilibrium, $3\text{ moles}$ of $\mathrm{HI}$ were found. The equilibrium constant for ${\mathrm{H}}_2(g)+{\mathrm{I}}_2(g)\rightleftharpoons 2\mathrm{HI}(g)$ is _________.

The number of molecules and moles in 2.8375 litres of ${\text{O}}_2$ at STP are respectively

1. A.$1.505\times 10^{23}$ and $0.250\text{ mol}$
2. B.$7.527\times 10^{22}$ and $0.250\text{ mol}$
3. C.$7.527\times 10^{23}$ and $0.125\text{ mol}$
4. D.$7.527\times 10^{22}$ and $0.125\text{ mol}$

Match List I with List II $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ \text{A.}& 16{\text{ g of CH}}_4\text{ (g)}& \text{I.}& \text{Weighs 28 g}\\ \text{B.}& 1{\text{ g of H}}_2\text{ (g)}& \text{II.}& 60.2\times 10^{23}\text{ electrons}\\ \text{C.}& 1{\text{ mole of N}}_2\text{ (g)}& \text{III.}& \text{Weighs 32 g}\\ \text{D.}& 0.5{\text{ mol of SO}}_2\text{ (g)}& \text{IV.}& \text{Occupies 11.4 L volume at STP}\end{array}$$ Choose the correct answer from the options given below:

1. A.A-II, B-III, C-IV, D-I
2. B.A-II, B-IV, C-I, D-III
3. C.A-I, B-III, C-II, D-IV
4. D.A-II, B-IV, C-III, D-I

Match List I with List II: $$\begin{array}{llll}& \text{LIST I (Species)}& & \text{LIST II (Maximum allowed concentration in ppm in drinking water)}\\ \text{A.}& {\mathrm{F}}^{-}& \text{I.}& <50\text{ ppm}\\ \text{B.}& \mathrm{S}{\mathrm{O}}_4^{2-}& \text{II.}& <5\text{ ppm}\\ \text{C.}& \mathrm{N}{\mathrm{O}}_3^{-}& \text{III.}& <2\text{ ppm}\\ \text{D.}& \mathrm{Zn}& \text{IV.}& <500\text{ ppm}\end{array}$$ Choose the correct answer from the options given below :

1. A.A-IV, B-III, C-II, D-I
2. B.A-I, B-II, C-III, D-IV
3. C.A-II, B-I, C-III, D-IV
4. D.A-III, B-IV, C-I, D-II

If 5 moles of ${\text{BaCl}}_2$ is mixed with 2 moles of ${\text{Na}}_3{\text{PO}}_4$, the maximum number of moles of ${\text{Ba}}_3({\text{PO}}_4{)}_2$ formed is ________ (Nearest integer)

Number of isomeric compounds with molecular formula ${\text{C}}_9{\text{H}}_{10}\text{O}$ which (i) do not dissolve in $\text{NaOH}$ (ii) do not dissolve in $\text{HCl}$. (iii) do not give orange precipitate with 2,4-DNP (iv) on hydrogenation give identical compound with molecular formula ${\text{C}}_9{\text{H}}_{12}\text{O}$ is ________.

The density of 3M solution of $\text{NaCl}$ is $1.0{\text{ g mL}}^{-1}$. Molality of the solution is ________ $\times 10^{-2}\text{ m}$. (Nearest integer). Given: Molar mass of Na and Cl is 23 and $35.5{\text{ g mol}}^{-1}$ respectively.

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

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 $A$ ?

1. A.${\mathrm{C}}_9{\mathrm{H}}_8$
2. B.${\mathrm{C}}_5{\mathrm{H}}_8$
3. C.${\mathrm{C}}_{11}{\mathrm{H}}_4$
4. D.${\mathrm{C}}_{11}{\mathrm{H}}_8$

Some amount of dichloromethane $({\mathrm{CH}}_2{\mathrm{Cl}}_2)$ is added to $671.141\text{ mL}$ of chloroform $({\mathrm{CHCl}}_3)$ to prepare $2.6\times 10^{-3}\text{ M}$ solution of ${\mathrm{CH}}_2{\mathrm{Cl}}_2(\mathrm{DCM})$. The concentration of DCM is _________ ppm (by mass). Given : atomic mass : $\mathrm{C}=12$ $\mathrm{H}=1$ $\mathrm{Cl}=35.5$ density of ${\mathrm{CHCl}}_3=1.49{\text{ g cm}}^{-3}$

The energy of one mole of photons of radiation of frequency $2\times 10^{12}\text{ Hz}$ in ${\text{J mol}}^{-1}$ is ___________. (Nearest integer) $[\text{Given : }h=6.626\times 10^{-34}\text{ Js}$ ${\mathrm{N}}_{\mathrm{A}}=6.022\times 10^{23}{\text{ mol}}^{-1}]$

Solid Lead nitrate is dissolved in 1 litre of water. The solution was found to boil at $100.15^{\circ }\mathrm{C}$. When 0.2 mol of NaCl is added to the resulting solution, it was observed that the solution froze at $-0.8^{\circ }$ C. The solubility product of $\mathrm{PbC}{\mathrm{l}}_2$ formed is ____ $\times 10^{-6}$ at 298 K. (Nearest integer) Given : ${\mathrm{K}}_{\mathrm{b}}=0.5\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$ and ${\mathrm{K}}_{\mathrm{f}}=1.8\mathrm{K}\mathrm{kg}\mathrm{mo}{\mathrm{l}}^{-1}$. Assume molality to be equal to molarity in all cases.

When a hydrocarbon A undergoes combustion in the presence of air, it requires 9.5 equivalents of oxygen and produces 3 equivalents of water. What is the molecular formula of A?

1. A.${\mathrm{C}}_9{\mathrm{H}}_6$
2. B.${\mathrm{C}}_6{\mathrm{H}}_6$
3. C.${\mathrm{C}}_8{\mathrm{H}}_6$
4. D.${\mathrm{C}}_9{\mathrm{H}}_9$

The concentration of dissolved Oxygen in water for growth of fish should be more than $\underline{\text{X}}$ ppm and Biochemical Oxygen Demand in clean water should be less than $\underline{\text{Y}}$ ppm. X and Y in ppm are, respectively.

1. A.$$\begin{array}{cc}\mathrm{X}& \mathrm{Y}\\ 4& 15\end{array}$$
2. B.$$\begin{array}{cc}\mathrm{X}& \mathrm{Y}\\ 4& 8\end{array}$$
3. C.$$\begin{array}{cc}\mathrm{X}& \mathrm{Y}\\ 6& 12\end{array}$$
4. D.$$\begin{array}{cc}\mathrm{X}& \mathrm{Y}\\ 6& 5\end{array}$$

When $\mathrm{F}{\mathrm{e}}_{0.93}\mathrm{O}$ is heated in presence of oxygen, it converts to $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3$. The number of correct statement/s from the following is ____ A. The equivalent weight of $\mathrm{F}{\mathrm{e}}_{0.93}\mathrm{O}$ is $\frac{\text{Molecular weight}}{0.79}$ B. The number of moles of $\mathrm{F}{\mathrm{e}}^{2+}$ and $\mathrm{F}{\mathrm{e}}^{3+}$ in 1 mole of $\mathrm{F}{\mathrm{e}}_{0.93}\mathrm{O}$ is 0.79 and 0.14 respectively C. $\mathrm{F}{\mathrm{e}}_{0.93}\mathrm{O}$ is metal deficient with lattice comprising of cubic closed packed arrangement of ${\mathrm{O}}^{2-}$ ions D. The % composition of $\mathrm{F}{\mathrm{e}}^{2+}$ and $\mathrm{F}{\mathrm{e}}^{3+}$ in $\mathrm{F}{\mathrm{e}}_{0.93}\mathrm{O}$ is 85% and 15% respectively

The number of units, which are used to express concentration of solutions from the following is _________ Mass percent, Mole, Mole fraction, Molarity, ppm, Molality

The total pressure observed by mixing two liquids A and B is 350 mm Hg when their mole fractions are 0.7 and 0.3 respectively. The total pressure becomes 410 mm Hg if the mole fractions are changed to 0.2 and 0.8 respectively for A and B. The vapour pressure of pure A is __________ mm Hg. (Nearest integer) Consider the liquids and solutions behave ideally.

$${\mathrm{N}}_{2(\mathrm{g})}+3{\mathrm{H}}_{2(\mathrm{g})}\rightleftharpoons 2N{\mathrm{H}}_{3(\mathrm{g})}$$ $20\mathrm{g}5\mathrm{g}$ Consider the above reaction, the limiting reagent of the reaction and number of moles of $\mathrm{N}{\mathrm{H}}_3$ formed respectively are :

1. A.${\mathrm{H}}_2$, 1.42 moles
2. B.${\mathrm{H}}_2$, 0.71 moles
3. C.${\mathrm{N}}_2$, 1.42 moles
4. D.${\mathrm{N}}_2$, 0.71 moles

In the given reaction, $$X+Y+3Z\leftrightarrows XY{Z}_3$$ if one mole of each of $X$ and $Y$ with $0.05\text{ mol}$ of $Z$ gives compound $XY{Z}_3$. (Given : Atomic masses of $X,Y$ and $Z$ are 10, 20 and 30 amu, respectively.) The yield of $XY{Z}_3$ is _________ g. (Nearest integer)

$2\mathrm{L}$ of $0.2\mathrm{M}{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ is reacted with $2\mathrm{L}$ of $0.1\mathrm{M}\mathrm{NaOH}$ solution, the molarity of the resulting product $\mathrm{N}{\mathrm{a}}_2\mathrm{S}{\mathrm{O}}_4$ in the solution is ____ millimolar. (Nearest integer)

A gaseous mixture of two substances A and B, under a total pressure of $0.8\mathrm{atm}$ is in equilibrium with an ideal liquid solution. The mole fraction of substance A is $0.5$ in the vapour phase and $0.2$ in the liquid phase. The vapour pressure of pure liquid A is ____ atm. (Nearest integer)

$20\text{ mL}$ of $0.02\text{ M }{\mathrm{K}}_2\mathrm{C}{\mathrm{r}}_2{\mathrm{O}}_7$ solution is used for the titration of $10\text{ mL}$ of ${\mathrm{Fe}}^{2+}$ solution in the acidic medium. The molarity of ${\mathrm{Fe}}^{2+}$ solution is _________ $\times 10^{-2}\text{ M}$. (Nearest Integer)

The normality of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ in the solution obtained on mixing $100\mathrm{mL}$ of $0.1\mathrm{M}{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ with $50\mathrm{mL}$ of $0.1\mathrm{M}\mathrm{NaOH}$ is ____ $\times 10^{-1}\mathrm{N}$. (Nearest Integer)