Mole Concept & Stoichiometry · JEE Main previous year questions

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2022 21 questions

Q622022 · 29 Jul 2022 · Shift 1
$N_{2 (g)} + 3 H_{2 (g)} ⇌ 2N H_{3 (g)}$ $20 g 5 g$ Consider the above reaction, the limiting reagent of the reaction and number of moles of $N H_{3}$ formed respectively are :
1. A. $H_{2}$ , 1.42 moles
2. B. $H_{2}$ , 0.71 moles
3. C. $N_{2}$ , 1.42 moles
4. D. $N_{2}$ , 0.71 moles
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Answer: C
Q812022 · 28 Jul 2022 · Shift 1· Numerical answer
In the given reaction, $X + Y + 3 Z ⇆ X Y Z_{3}$ if one mole of each of $X$ and $Y$ with $0.05 mol$ of $Z$ gives compound $X Y Z_{3}$ . (Given : Atomic masses of $X, Y$ and $Z$ are 10, 20 and 30 amu, respectively.) The yield of $X Y Z_{3}$ is _________ g. (Nearest integer)
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Answer: 2
Q812022 · 28 Jul 2022 · Shift 2· Numerical answer
$2 L$ of $0.2 M H_{2} S O_{4}$ is reacted with $2 L$ of $0.1 M NaOH$ solution, the molarity of the resulting product $N a_{2} S O_{4}$ in the solution is ____ millimolar. (Nearest integer)
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Answer: 25
Q832022 · 28 Jul 2022 · Shift 2· Numerical answer
A gaseous mixture of two substances A and B, under a total pressure of $0.8 atm$ 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)
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Answer: 2
Q812022 · 27 Jul 2022 · Shift 1· Numerical answer
$20 mL$ of $0.02 M K_{2} C r_{2} O_{7}$ solution is used for the titration of $10 mL$ of $Fe^{2 +}$ solution in the acidic medium. The molarity of $Fe^{2 +}$ solution is _________ $\times 1 0^{- 2} M$ . (Nearest Integer)
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Answer: 24
Q812022 · 27 Jul 2022 · Shift 2· Numerical answer
The normality of $H_{2} S O_{4}$ in the solution obtained on mixing $100 mL$ of $0.1 M H_{2} S O_{4}$ with $50 mL$ of $0.1 M NaOH$ is ____ $\times 1 0^{- 1} N$ . (Nearest Integer)
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Answer: 1
Q832022 · 27 Jul 2022 · Shift 2· Numerical answer
When a certain amount of solid A is dissolved in $100 g$ of water at $2 5^{\circ} C$ to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is $23.76 mmHg$ . The number of moles of solute A added is ____. (Nearest Integer)
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Answer: 6
Q842022 · 26 Jul 2022 · Shift 1· Numerical answer
When $800 mL$ of $0.5 M$ nitric acid is heated in a beaker, its volume is reduced to half and $11.5 g$ of nitric acid is evaporated. The molarity of the remaining nitric acid solution is $x \times 1 0^{- 2} M$ . (Nearest integer) (Molar mass of nitric acid is $63 g mo l^{- 1}$ )
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Answer: 54
Q862022 · 26 Jul 2022 · Shift 1· Numerical answer
The amount of charge in $F$ (Faraday) required to obtain one mole of iron from $F e_{3} O_{4}$ is ____. (Nearest Integer)
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Answer: 3
Q892022 · 25 Jul 2022 · Shift 2· Numerical answer
The total number of monobromo derivatives formed by the alkanes with molecular formula $C_{5} H_{12}$ is (excluding stereo isomers) ____ .
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Answer: 8
Q752022 · 30 Jun 2022 · Shift 1
An element X has a body centred cubic (bcc) structure with a cell edge of $200 pm$ . The density of the element is $5 g cm^{- 3}$ . The number of atoms present in $300 g$ of the element X is ____________. Given : Avogadro constant, $N_{A} = 6.0 \times 1 0^{23} mol^{- 1}$ .
1. A. $5 N_{A}$
2. B. $6 N_{A}$
3. C. $15 N_{A}$
4. D. $25 N_{A}$
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Answer: D
Q612022 · 28 Jun 2022 · Shift 2
Compound A contains 8.7% Hydrogen, 74% Carbon and 17.3% Nitrogen. The molecular formula of the compound is, Given : Atomic masses of C, H and N are 12, 1 and 14 amu respectively. The molar mass of the compound A is $162 g mo l^{- 1}$ .
1. A. $C_{4} H_{6} N_{2}$
2. B. $C_{2} H_{3} N$
3. C. $C_{5} H_{7} N$
4. D. $C_{10} H_{14} N_{2}$
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Answer: D
Q612022 · 27 Jun 2022 · Shift 1
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : At $1 0^{\circ} C$ , the density of a $5 M$ solution of $KCl$ [atomic masses of $K$ & $Cl$ are 39 & $35.5 g mo l^{- 1}$ respectively], is ' $x$ ' $g m l^{- 1}$ . The solution is cooled to $- 2 1^{\circ} C$ . The molality of the solution will remain unchanged. Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature. In the light of the above statements, choose the correct answer from the options given below :
1. A.Both (A) and (R) are true and (R) is the correct explanation of (A).
2. B.Both (A) and (R) are true but (R) is not the correct explanation of (A).
3. C.(A) is true but (R) is false.
4. D.(A) is false but (R) is true.
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Answer: A
Q832022 · 27 Jun 2022 · Shift 1· Numerical answer
$2 NOCl (g) ⇌ 2 NO (g) + C l_{2} (g)$ In an experiment, $2.0 moles$ of $NOCl$ was placed in a one-litre flask and the concentration of $NO$ after equilibrium established, was found to be $0.4 mol/L$ . The equilibrium constant at $3 0^{\circ} C$ is ____ $\times 1 0^{- 4}$ .
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Answer: 125
Q882022 · 27 Jun 2022 · Shift 1· Numerical answer
Two elements A and B which form $0.15 moles$ of $A_{2} B$ and $A B_{3}$ type compounds. If both $A_{2} B$ and $A B_{3}$ weigh equally, then the atomic weight of A is ____ times of atomic weight of B.
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Answer: 2
Q832022 · 27 Jun 2022 · Shift 2· Numerical answer
When $5 moles$ of He gas expand isothermally and reversibly at $300 K$ from $10 litre$ to $20 litre$ , the magnitude of the maximum work obtained is ________ J. [nearest integer] (Given : $R = 8.3 J K^{- 1} mol^{- 1}$ and $lo g 2 = 0.3010$ )
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Answer: 8630
Q612022 · 26 Jun 2022 · Shift 1
A commercially sold conc. HCl is 35% HCl by mass. If the density of this commercial acid is 1.46 g/mL, the molarity of this solution is: (Atomic mass : Cl = 35.5 amu, H = 1 amu)
1. A.10.2 M
2. B.12.5 M
3. C.14.0 M
4. D.18.2 M
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Answer: C
Q842022 · 26 Jun 2022 · Shift 1· Numerical answer
A flask is filled with equal moles of A and B. The half lives of A and B are 100 s and 50 s respectively and are independent of the initial concentration. The time required for the concentration of A to be four times that of B is ___________ s. (Given : ln 2 = 0.693)
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Answer: 200
Q892022 · 26 Jun 2022 · Shift 2· Numerical answer
The moles of methane required to produce $81 g$ of water after complete combustion is ____ $\times 1 0^{- 2} mol$ . [nearest integer]
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Answer: 225
Q902022 · 26 Jun 2022 · Shift 2· Numerical answer
In a solid $AB$ , $A$ atoms are in ccp arrangement and $B$ atoms occupy all the octahedral sites. If two atoms from the opposite faces are removed, then the resultant stoichiometry of the compound is $A_{x} B_{y}$ . The value of $x$ is ____. [nearest integer]
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Answer: 3
Q622022 · 24 Jun 2022 · Shift 2
The energy of one mole of photons of radiation of wavelength $300 nm$ is (Given : $h = 6.63 \times 1 0^{- 34} J s$ , $N_{A} = 6.02 \times 1 0^{23} mol^{- 1}$ , $c = 3 \times 1 0^{8} m s^{- 1}$ )
1. A. $235 kJ mol^{- 1}$
2. B. $325 kJ mol^{- 1}$
3. C. $399 kJ mol^{- 1}$
4. D. $435 kJ mol^{- 1}$
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Answer: C