Mole Concept & Stoichiometry · JEE Main previous year questions

Molality of an aqueous solution of urea is $4.44\text{ m}$. Mole fraction of urea in solution is $x\times 10^{-3}$, Value of $x$ is ______. (Integer answer)

Molality (m) of $3\text{M}$ aqueous solution of $\text{NaCl}$ is : (Given : Density of solution $=1.25{\text{ g mL}}^{-1}$, Molar mass in ${\text{g mol}}^{-1}:\text{Na}-23,\text{Cl}-35.5$)

1. A.$2.90\text{ m}$
2. B.$3.85\text{ m}$
3. C.$1.90\text{ m}$
4. D.$2.79\text{ m}$

The number of moles of methane required to produce $11\mathrm{g}\mathrm{C}{\mathrm{O}}_2(\mathrm{g})$ after complete combustion is : (Given molar mass of methane in $\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}:16$ )

1. A.0.35
2. B.0.25
3. C.0.5
4. D.0.75

Combustion of 1 mole of benzene is expressed as ${\mathrm{C}}_6{\mathrm{H}}_6(\mathrm{l})+\frac{15}{2}{\mathrm{O}}_2(\mathrm{g})\to 6\mathrm{C}{\mathrm{O}}_2(\mathrm{g})+3{\mathrm{H}}_2\mathrm{O}(\mathrm{l})$. The standard enthalpy of combustion of 2 mol of benzene is ${-}^{\prime }{x}^{\prime }\mathrm{kJ}$. $x=$ ____. Given : 1. standard Enthalpy of formation of 1 mol of ${\mathrm{C}}_6{\mathrm{H}}_6(\mathrm{l})$, for the reaction $6\mathrm{C}(\mathrm{graphite})+3{\mathrm{H}}_2(\mathrm{g})\to {\mathrm{C}}_6{\mathrm{H}}_6(\mathrm{l})$ is $48.5\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. 2. Standard Enthalpy of formation of 1 mol of $\mathrm{C}{\mathrm{O}}_2(\mathrm{g})$, for the reaction $\mathrm{C}(\mathrm{graphite})+{\mathrm{O}}_2(\mathrm{g})\to \mathrm{C}{\mathrm{O}}_2(\mathrm{g})$ is $-393.5\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$. 3. Standard Enthalpy of formation of 1 mol of ${\mathrm{H}}_2\mathrm{O}(\mathrm{l})$, for the reaction ${\mathrm{H}}_2(\mathrm{g})+\frac{1}{2}{\mathrm{O}}_2(\mathrm{g})\to {\mathrm{H}}_2\mathrm{O}(\mathrm{l})$ is $-286\mathrm{kJ}\mathrm{mo}{\mathrm{l}}^{-1}$.

The Molarity (M) of an aqueous solution containing $5.85\mathrm{g}$ of $\mathrm{NaCl}$ in $500\mathrm{mL}$ water is : (Given : Molar Mass $\mathrm{Na}:23$ and $\mathrm{Cl}:35.5\mathrm{gmo}{\mathrm{l}}^{-1}$)

1. A.20
2. B.4
3. C.2
4. D.0.2

Only $2\mathrm{mL}$ of $\mathrm{KMn}{\mathrm{O}}_4$ solution of unknown molarity is required to reach the end point of a titration of $20\mathrm{mL}$ of oxalic acid $(2\mathrm{M})$ in acidic medium. The molarity of $\mathrm{KMn}{\mathrm{O}}_4$ solution should be ____ $\mathrm{M}$.

Three moles of an ideal gas are compressed isothermally from $60\text{ L}$ to $20\text{ L}$ using constant pressure of $5\text{ atm}$. Heat exchange Q for the compression is - ________ Lit. atm.

One Faraday of electricity liberates $x\times 10^{-1}$ gram atom of copper from copper sulphate. $x$ is ____.

Number of moles of methane required to produce $22\mathrm{g}\mathrm{C}{\mathrm{O}}_{2(\mathrm{g})}$ after combustion is $\mathrm{x}\times 10^{-2}$ moles. The value of $\mathrm{x}$ is ____.

Number of moles of ${\mathrm{H}}^{+}$ ions required by $1$ mole of $\mathrm{Mn}{\mathrm{O}}_4^{-}$ to oxidise oxalate ion to $\mathrm{C}{\mathrm{O}}_2$ is ____.

If 5 moles of an ideal gas expands from $10\mathrm{L}$ to a volume of $100\mathrm{L}$ at $300\mathrm{K}$ under isothermal and reversible condition then work, $\mathrm{w}$, is $-x$ J. The value of $x$ is ____. (Given R = 8.314 J ${\mathrm{K}}^{-1}$ $\mathrm{mo}{\mathrm{l}}^{-1}$)

The molarity of $1\mathrm{L}$ orthophosphoric acid $({\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4)$ having $70\%$ purity by weight (specific gravity $1.54\mathrm{g}\mathrm{c}{\mathrm{m}}^{-3}$) is ____ $\mathrm{M}$. (Molar mass of ${\mathrm{H}}_3\mathrm{P}{\mathrm{O}}_4=98\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$)

A solution of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ is $31.4\%{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ by mass and has a density of $1.25\text{ g/mL}$. The molarity of the ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ solution is _________ M (nearest integer) [Given molar mass of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4=98{\text{ g mol}}^{-1}$]

Molality of 0.8 M ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ solution (density $1.06{\text{ g cm}}^{-3}$) is _________ $\times 10^{-3}\text{ m}$.

If three moles of an ideal gas at $300\text{ K}$ expand isothermally from $30{\text{ dm}}^3$ to $45{\text{ dm}}^3$ against a constant opposing pressure of $80\text{ kPa}$, then the amount of heat transferred is _______ $\text{J}$.

The molecular formula of second homologue in the homologous series of mono carboxylic acids is

1. A.${\text{C}}_2{\text{H}}_4{\text{O}}_2$
2. B.${\text{C}}_2{\text{H}}_2{\text{O}}_2$
3. C.${\text{CH}}_2\text{O}$
4. D.${\text{C}}_3{\text{H}}_6{\text{O}}_2$

1 mole of $\text{PbS}$ is oxidised by "X" moles of ${\text{O}}_3$ to get "Y" moles of ${\text{O}}_2$. $\text{X}+\text{Y}=$ _______.

A metal chloride contains $55.0\%$ of chlorine by weight. $100\text{ mL}$ vapours of the metal chloride at STP weigh $0.57\text{ g}$. The molecular formula of the metal chloride is (Given: Atomic mass of chlorine is $35.5\mathrm{u}$)

1. A.$\mathrm{MC}{\mathrm{l}}_2$
2. B.$\mathrm{MC}{\mathrm{l}}_4$
3. C.$\mathrm{MC}{\mathrm{l}}_3$
4. D.$\mathrm{MCl}$

80 mole percent of $\mathrm{MgC}{\mathrm{l}}_2$ is dissociated in aqueous solution. The vapour pressure of $1.0\text{ molal}$ aqueous solution of $\mathrm{MgC}{\mathrm{l}}_2$ at $38^{\circ }\mathrm{C}$ is _________ $\text{mm Hg}$. (Nearest integer) Given : Vapour pressure of water at $38^{\circ }\mathrm{C}$ is $50\text{ mm Hg}$

Given below are two statements: Statement I : If BOD is $4\text{ ppm}$ and dissolved oxygen is $8\text{ ppm}$, then it is a good quality water. Statement II : If the concentration of zinc and nitrate salts are $5\text{ ppm}$ each, then it can be a good quality water. In the light of the above statements, choose the most appropriate answer from the options given below :

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

A solution of sugar is obtained by mixing $200\text{ g}$ of its $25\%$ solution and $500\text{ g}$ of its $40\%$ solution (both by mass). The mass percentage of the resulting sugar solution is _________ (Nearest integer)

A solution is prepared by adding $2\text{ g}$ of "X" to $1\text{ mole}$ of water. Mass percent of "X" in the solution is :

1. A.$20\%$
2. B.$10\%$
3. C.$2\%$
4. D.$5\%$

One mole of ${\mathrm{P}}_4$ reacts with 8 moles of $\mathrm{SOC}{\mathrm{l}}_2$ to give 4 moles of A, $x$ mole of $\mathrm{S}{\mathrm{O}}_2$ and 2 moles of B. A, B and $x$ respectively are :

1. A.$\mathrm{POC}{\mathrm{l}}_3$, ${\mathrm{S}}_2\mathrm{C}{\mathrm{l}}_2$ and $4$
2. B.$\mathrm{PC}{\mathrm{l}}_3$, ${\mathrm{S}}_2\mathrm{C}{\mathrm{l}}_2$ and $4$
3. C.$\mathrm{POC}{\mathrm{l}}_3$, ${\mathrm{S}}_2\mathrm{C}{\mathrm{l}}_2$ and $2$
4. D.$\mathrm{PC}{\mathrm{l}}_3$, ${\mathrm{S}}_2\mathrm{C}{\mathrm{l}}_2$ and $2$

The total number of intensive properties from the following is _________ Volume, Molar heat capacity, Molarity, ${\mathrm{E}}^{\theta }$ cell, Gibbs free energy change, Molar mass, Mole