Mole Concept & Stoichiometry · JEE Main previous year questions

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2024 20 questions

Q672024 · 9 Apr 2024 · Shift 1
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) $KMn O_{4}$ & $NaOH$ 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
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Answer: A
Q902024 · 9 Apr 2024 · Shift 1· Numerical answer
Molarity $(M)$ of an aqueous solution containing $x g$ of anhyd. $CuS O_{4}$ in $500 mL$ solution at $3 2^{\circ} C$ is $2 \times 1 0^{- 1} M$ . Its molality will be ____ $\times 1 0^{- 3} m$ . (nearest integer). [Given density of the solution $= 1.25 g/mL$ ]
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Answer: 164
Q872024 · 8 Apr 2024 · Shift 2· Numerical answer
A solution is prepared by adding $1 mole$ ethyl alcohol in $9 mole$ water. The mass percent of solute in the solution is ______ (Integer answer) (Given : Molar mass in $g mol^{- 1}$ Ethyl alcohol : $46$ water : $18$ )
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Answer: 22
Q882024 · 8 Apr 2024 · Shift 2· Numerical answer
Molality of an aqueous solution of urea is $4.44 m$ . Mole fraction of urea in solution is $x \times 1 0^{- 3}$ , Value of $x$ is ______. (Integer answer)
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Answer: 74
Q722024 · 6 Apr 2024 · Shift 2
Molality (m) of $3 M$ aqueous solution of $NaCl$ is : (Given : Density of solution $= 1.25 g mL^{- 1}$ , Molar mass in $g mol^{- 1} : Na - 23, Cl - 35.5$ )
1. A. $2.90 m$
2. B. $3.85 m$
3. C. $1.90 m$
4. D. $2.79 m$
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Answer: D
Q762024 · 5 Apr 2024 · Shift 2
The number of moles of methane required to produce $11 g C O_{2} (g)$ after complete combustion is : (Given molar mass of methane in $g mo l^{- 1} : 16$ )
1. A.0.35
2. B.0.25
3. C.0.5
4. D.0.75
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Answer: B
Q882024 · 5 Apr 2024 · Shift 2· Numerical answer
Combustion of 1 mole of benzene is expressed as $C_{6} H_{6} (l) + \frac{15}{2} O_{2} (g) \to 6 C O_{2} (g) + 3 H_{2} O (l)$ . The standard enthalpy of combustion of 2 mol of benzene is $-^{'} x^{'} kJ$ . $x =$ ____. Given : 1. standard Enthalpy of formation of 1 mol of $C_{6} H_{6} (l)$ , for the reaction $6 C (graphite) + 3 H_{2} (g) \to C_{6} H_{6} (l)$ is $48.5 kJ mo l^{- 1}$ . 2. Standard Enthalpy of formation of 1 mol of $C O_{2} (g)$ , for the reaction $C (graphite) + O_{2} (g) \to C O_{2} (g)$ is $- 393.5 kJ mo l^{- 1}$ . 3. Standard Enthalpy of formation of 1 mol of $H_{2} O (l)$ , for the reaction $H_{2} (g) + \frac{1}{2} O_{2} (g) \to H_{2} O (l)$ is $- 286 kJ mo l^{- 1}$ .
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Answer: 6535
Q732024 · 4 Apr 2024 · Shift 1
The Molarity (M) of an aqueous solution containing $5.85 g$ of $NaCl$ in $500 mL$ water is : (Given : Molar Mass $Na : 23$ and $Cl : 35.5 gmo l^{- 1}$ )
1. A.20
2. B.4
3. C.2
4. D.0.2
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Answer: D
Q822024 · 4 Apr 2024 · Shift 1· Numerical answer
Only $2 mL$ of $KMn O_{4}$ solution of unknown molarity is required to reach the end point of a titration of $20 mL$ of oxalic acid $(2 M)$ in acidic medium. The molarity of $KMn O_{4}$ solution should be ____ $M$ .
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Answer: 8
Q872024 · 4 Apr 2024 · Shift 2· Numerical answer
Three moles of an ideal gas are compressed isothermally from $60 L$ to $20 L$ using constant pressure of $5 atm$ . Heat exchange Q for the compression is - ________ Lit. atm.
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Answer: 200
Q862024 · 31 Jan 2024 · Shift 1· Numerical answer
One Faraday of electricity liberates $x \times 1 0^{- 1}$ gram atom of copper from copper sulphate. $x$ is ____.
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Answer: 5
Q872024 · 31 Jan 2024 · Shift 1· Numerical answer
Number of moles of methane required to produce $22 g C O_{2 (g)}$ after combustion is $x \times 1 0^{- 2}$ moles. The value of $x$ is ____.
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Answer: 50
Q872024 · 31 Jan 2024 · Shift 2· Numerical answer
Number of moles of $H^{+}$ ions required by $1$ mole of $Mn O_{4}^{-}$ to oxidise oxalate ion to $C O_{2}$ is ____.
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Answer: 8
Q882024 · 31 Jan 2024 · Shift 2· Numerical answer
If 5 moles of an ideal gas expands from $10 L$ to a volume of $100 L$ at $300 K$ under isothermal and reversible condition then work, $w$ , is $- x$ J. The value of $x$ is ____. (Given R = 8.314 J $K^{- 1}$ $mo l^{- 1}$ )
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Answer: 28721
Q892024 · 31 Jan 2024 · Shift 2· Numerical answer
The molarity of $1 L$ orthophosphoric acid $(H_{3} P O_{4})$ having $70%$ purity by weight (specific gravity $1.54 g c m^{- 3}$ ) is ____ $M$ . (Molar mass of $H_{3} P O_{4} = 98 g mo l^{- 1}$ )
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Answer: 11
Q822024 · 29 Jan 2024 · Shift 1· Numerical answer
A solution of $H_{2} S O_{4}$ is $31.4% H_{2} S O_{4}$ by mass and has a density of $1.25 g/mL$ . The molarity of the $H_{2} S O_{4}$ solution is _________ M (nearest integer) [Given molar mass of $H_{2} S O_{4} = 98 g mol^{- 1}$ ]
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Answer: 4
Q902024 · 29 Jan 2024 · Shift 2· Numerical answer
Molality of 0.8 M $H_{2} S O_{4}$ solution (density $1.06 g cm^{- 3}$ ) is _________ $\times 1 0^{- 3} m$ .
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Answer: 815
Q842024 · 27 Jan 2024 · Shift 1· Numerical answer
If three moles of an ideal gas at $300 K$ expand isothermally from $30 dm^{3}$ to $45 dm^{3}$ against a constant opposing pressure of $80 kPa$ , then the amount of heat transferred is _______ $J$ .
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Answer: 1200
Q802024 · 27 Jan 2024 · Shift 2
The molecular formula of second homologue in the homologous series of mono carboxylic acids is
1. A. $C_{2} H_{4} O_{2}$
2. B. $C_{2} H_{2} O_{2}$
3. C. $CH_{2} O$
4. D. $C_{3} H_{6} O_{2}$
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Answer: A
Q812024 · 27 Jan 2024 · Shift 2· Numerical answer
1 mole of $PbS$ is oxidised by "X" moles of $O_{3}$ to get "Y" moles of $O_{2}$ . $X + Y =$ _______.
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Answer: 8