Mole Concept & Stoichiometry · JEE Main previous year questions

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2025 18 questions

Q742025 · 8 Apr 2025 · Shift 2· Numerical answer
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) $(Given : Na = 23, I = 127, Ag = 108, N = 14, O = 16 g mo l^{- 1})$
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Answer: 1
Q652025 · 4 Apr 2025 · Shift 1
An organic compound (X) with molecular formula $C_{3} H_{6} O$ is not readily oxidised. On reduction it gives $C_{3} H_{8} O (Y)$ 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. $C H_{3} C H_{2} CHO, C H_{3} C H_{2} C H_{2} OH, C H_{3} C H_{2} C H_{2} Br$
2. B. $C H_{3} COC H_{3}, C H_{3} CH (OH) C H_{3}, C H_{3} CH (Br) C H_{3}$
3. C. $C H_{3} COC H_{3}, C H_{3} C H_{2} C H_{2} OH, C H_{3} CH (Br) C H_{3}$
4. D. $C H_{3} C H_{2} CHO, C H_{3} CH = C H_{2}, C H_{3} CH (Br) C H_{3}$
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Answer: B
Q712025 · 4 Apr 2025 · Shift 2· Numerical answer
Sea water, which can be considered as a 6 molar ( $6 M$ ) solution of $NaCl$ , has a density of $2 g mL^{- 1}$ . The concentration of dissolved oxygen ( $O_{2}$ ) in sea water is $5.8 ppm$ . Then the concentration of dissolved oxygen ( $O_{2}$ ) in sea water, in terms of molality, is $x \times 1 0^{- 4} m$ . $x =$ . (Nearest integer) Given: Molar mass of $NaCl$ is $58.5 g mol^{- 1}$ Molar mass of $O_{2}$ is $32 g mol^{- 1}$
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Answer: 2
Q572025 · 3 Apr 2025 · Shift 2
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
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Answer: B
Q722025 · 3 Apr 2025 · Shift 2· Numerical answer
The total number of structural isomers possible for the substituted benzene derivatives with the molecular formula $C_{9} H_{12}$ is__________.
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Answer: 8
Q572025 · 2 Apr 2025 · Shift 1
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 $200 mm Hg$ and that of the solution is $500 mm Hg$ . 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
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Answer: C
Q602025 · 2 Apr 2025 · Shift 1
On complete combustion $1.0 g$ of an organic compound $(X)$ gave $1.46 g$ of $CO_{2}$ and $0.567 g$ of $H_{2} O$ . The empirical formula mass of compound $(X)$ is _________ g. (Given molar mass in $gmol^{- 1} C : 12, H : 1, O : 16$ )
1. A.60
2. B.45
3. C.30
4. D.15
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Answer: C
Q662025 · 2 Apr 2025 · Shift 2
1. A.
2. B.
3. C.
4. D.
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Answer: D
Q552025 · 29 Jan 2025 · Shift 2
$0.1 M$ solution of $KI$ reacts with excess of $H_{2} S O_{4}$ and $KI O_{3}$ solutions. According to equation $5 I^{-} + I O_{3}^{-} + 6 H^{+} \to 3 I_{2} + 3 H_{2} O$ Identify the correct statements : (A) $200 mL$ of $KI$ solution reacts with $0.004 mol$ of $KI O_{3}$ (B) $200 mL$ of $KI$ solution reacts with $0.006 mol$ of $H_{2} S O_{4}$ (C) $0.5 L$ of $KI$ solution produced $0.005 mol$ of $I_{2}$ (D) Equivalent weight of $KI O_{3}$ is equal to $(\frac{Molecular weight}{5})$ 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
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Answer: D
Q732025 · 28 Jan 2025 · Shift 1· Numerical answer
The molarity of a 70% (mass/mass) aqueous solution of a monobasic acid (X) is ____ $\times 1 0^{- 1} M$ (Nearest integer) [Given: Density of aqueous solution of (X) is $1.25 g m L^{- 1}$ Molar mass of the acid is $70 g mo l^{- 1}$ ]
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Answer: 125
Q752025 · 28 Jan 2025 · Shift 1· Numerical answer
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 ____ $\times 1 0^{- 1}$ (Given molar mass in $g mo l^{- 1}$ of C : 12, H : 1, O : 16, Cl : 35.5)
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Answer: 1655
Q622025 · 24 Jan 2025 · Shift 1
One mole of the octahedral complex compound $Co (N H_{3})_{5} C l_{3}$ gives 3 moles of ions on dissolution in water. One mole of the same complex reacts with excess of $AgN O_{3}$ solution to yield two moles of $AgC l_{(s)}$ . The structure of the complex is:
1. A. $[Co (N H_{3})_{5} Cl] C l_{2}$
2. B. $[Co (N H_{3})_{4} Cl] \cdot C l_{2} \cdot N H_{3}$
3. C. $[Co (N H_{3})_{3} C l_{3}] \cdot 2N H_{3}$
4. D. $[Co (N H_{3})_{4} C l_{2}] \cdot Cl \cdot N H_{3}$
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Answer: A
Q562025 · 24 Jan 2025 · Shift 2
The elemental composition of a compound is $54.2% C, 9.2% H$ and $36.6% O$ . If the molar mass of the compound is $132 g mol^{- 1}$ , the molecular formula of the compound is : [Given : The relative atomic mass of $C : H : O = 12 : 1 : 16$ ]
1. A. $C_{4} H_{8} O_{2}$
2. B. $C_{6} H_{12} O_{6}$
3. C. $C_{4} H_{9} O_{3}$
4. D. $C_{6} H_{12} O_{3}$
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Answer: D
Q522025 · 23 Jan 2025 · Shift 2
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
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Answer: D
Q542025 · 23 Jan 2025 · Shift 2
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. $\frac{P _{1}^{0}}{P _{2}^{0}}, \frac{P _{1}^{0} - P _{2}^{0}}{P _{2}^{0}}$
2. B. $\frac{P _{2}^{0}}{P _{1}^{0}}, \frac{P _{2}^{0} - P _{1}^{0}}{P _{1}^{0}}$
3. C. $\frac{P _{2}^{0}}{P _{1}^{0}}, \frac{P _{1}^{0} - P _{2}^{0}}{P _{1}^{0}}$
4. D. $\frac{P _{1}^{0}}{P _{2}^{0}}, \frac{P _{2}^{0} - P _{1}^{0}}{P _{2}^{0}}$
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Answer: D
Q712025 · 23 Jan 2025 · Shift 2· Numerical answer
$0.01 mole$ of an organic compound $(X)$ containing $10%$ hydrogen, on complete combustion produced $0.9 g H_{2} O$ . Molar mass of $(X)$ is ____ $g mo l^{- 1}$ .
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Answer: 100
Q752025 · 23 Jan 2025 · Shift 2· Numerical answer
A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with $KMn O_{4} ∣ H^{+}$ gives $C H_{3} - O ∥ C - C H_{3}, C H_{3} - O ∥ C - OH and C H_{3} - O ∥ C - C H_{2} C H_{2} - O ∥ C - OH.$ The total number of $σ$ bonds present in the compound ' $X$ ' is ____.
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Answer: 27
Q632025 · 22 Jan 2025 · Shift 1
Given below are two statements : Statement I : One mole of propyne reacts with excess of sodium to liberate half a mole of $H_{2}$ gas. Statement II : Four $g$ of propyne reacts with $NaNH_{2}$ to liberate $NH_{3}$ gas which occupies $224 mL$ 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
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Answer: D