Mole Concept & Stoichiometry · JEE Main previous year questions

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2023 27 questions

Q672023 · 12 Apr 2023 · Shift 1
A metal chloride contains $55.0%$ of chlorine by weight. $100 mL$ vapours of the metal chloride at STP weigh $0.57 g$ . The molecular formula of the metal chloride is (Given: Atomic mass of chlorine is $35.5 u$ )
1. A. $MC l_{2}$
2. B. $MC l_{4}$
3. C. $MC l_{3}$
4. D. $MCl$
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Answer: A
Q822023 · 12 Apr 2023 · Shift 1· Numerical answer
80 mole percent of $MgC l_{2}$ is dissociated in aqueous solution. The vapour pressure of $1.0 molal$ aqueous solution of $MgC l_{2}$ at $3 8^{\circ} C$ is _________ $mm Hg$ . (Nearest integer) Given : Vapour pressure of water at $3 8^{\circ} C$ is $50 mm Hg$
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Answer: 48
Q792023 · 11 Apr 2023 · Shift 1
Given below are two statements: Statement I : If BOD is $4 ppm$ and dissolved oxygen is $8 ppm$ , then it is a good quality water. Statement II : If the concentration of zinc and nitrate salts are $5 ppm$ 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
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Answer: C
Q812023 · 11 Apr 2023 · Shift 1· Numerical answer
A solution of sugar is obtained by mixing $200 g$ of its $25%$ solution and $500 g$ of its $40%$ solution (both by mass). The mass percentage of the resulting sugar solution is _________ (Nearest integer)
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Answer: 36
Q862023 · 11 Apr 2023 · Shift 1· Numerical answer
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Answer: 2
Q682023 · 11 Apr 2023 · Shift 2
A solution is prepared by adding $2 g$ of "X" to $1 mole$ of water. Mass percent of "X" in the solution is :
1. A. $20%$
2. B. $10%$
3. C. $2%$
4. D. $5%$
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Answer: B
Q802023 · 11 Apr 2023 · Shift 2
One mole of $P_{4}$ reacts with 8 moles of $SOC l_{2}$ to give 4 moles of A, $x$ mole of $S O_{2}$ and 2 moles of B. A, B and $x$ respectively are :
1. A. $POC l_{3}$ , $S_{2} C l_{2}$ and $4$
2. B. $PC l_{3}$ , $S_{2} C l_{2}$ and $4$
3. C. $POC l_{3}$ , $S_{2} C l_{2}$ and $2$
4. D. $PC l_{3}$ , $S_{2} C l_{2}$ and $2$
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Answer: B
Q832023 · 11 Apr 2023 · Shift 2· Numerical answer
The total number of intensive properties from the following is _________ Volume, Molar heat capacity, Molarity, $E^{θ}$ cell, Gibbs free energy change, Molar mass, Mole
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Answer: 4
Q862023 · 11 Apr 2023 · Shift 2· Numerical answer
$4.5 moles$ each of hydrogen and iodine is heated in a sealed ten litre vessel. At equilibrium, $3 moles$ of $HI$ were found. The equilibrium constant for $H_{2} (g) + I_{2} (g) ⇌ 2 HI (g)$ is _________.
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Answer: 1
Q622023 · 10 Apr 2023 · Shift 1
The number of molecules and moles in 2.8375 litres of $O_{2}$ at STP are respectively
1. A. $1.505 \times 1 0^{23}$ and $0.250 mol$
2. B. $7.527 \times 1 0^{22}$ and $0.250 mol$
3. C. $7.527 \times 1 0^{23}$ and $0.125 mol$
4. D. $7.527 \times 1 0^{22}$ and $0.125 mol$
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Answer: D
Q712023 · 10 Apr 2023 · Shift 2
Match List I with List II $A. B. C. D. List - I 16 g of CH_{4} (g) 1 g of H_{2} (g) 1 mole of N_{2} (g) 0.5 mol of SO_{2} (g) I. II. III. IV. List - II Weighs 28 g 60.2 \times 1 0^{23} electrons Weighs 32 g Occupies 11.4 L volume at STP$ 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
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Answer: B
Q752023 · 8 Apr 2023 · Shift 1
Match List I with List II: $A. B. C. D. LIST I (Species) F^{-} S O_{4}^{2 -} N O_{3}^{-} Zn I. II. III. IV. LIST II (Maximum allowed concentration in ppm in drinking water) < 50 ppm < 5 ppm < 2 ppm < 500 ppm$ 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
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Answer: D
Q882023 · 6 Apr 2023 · Shift 1· Numerical answer
If 5 moles of $BaCl_{2}$ is mixed with 2 moles of $Na_{3} PO_{4}$ , the maximum number of moles of $Ba_{3} (PO_{4})_{2}$ formed is ________ (Nearest integer)
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Answer: 1
Q872023 · 1 Feb 2023 · Shift 1· Numerical answer
Number of isomeric compounds with molecular formula $C_{9} H_{10} O$ which (i) do not dissolve in $NaOH$ (ii) do not dissolve in $HCl$ . (iii) do not give orange precipitate with 2,4-DNP (iv) on hydrogenation give identical compound with molecular formula $C_{9} H_{12} O$ is ________.
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Answer: 2
Q902023 · 1 Feb 2023 · Shift 1· Numerical answer
The density of 3M solution of $NaCl$ is $1.0 g mL^{- 1}$ . Molality of the solution is ________ $\times 1 0^{- 2} m$ . (Nearest integer). Given: Molar mass of Na and Cl is 23 and $35.5 g mol^{- 1}$ respectively.
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Answer: 364
Q742023 · 31 Jan 2023 · Shift 1
1. A.
2. B.
3. C.
4. D.
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Answer: D
Q612023 · 31 Jan 2023 · Shift 2
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. $C_{9} H_{8}$
2. B. $C_{5} H_{8}$
3. C. $C_{11} H_{4}$
4. D. $C_{11} H_{8}$
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Answer: A
Q812023 · 30 Jan 2023 · Shift 1· Numerical answer
Some amount of dichloromethane $(CH_{2} Cl_{2})$ is added to $671.141 mL$ of chloroform $(CHCl_{3})$ to prepare $2.6 \times 1 0^{- 3} M$ solution of $CH_{2} Cl_{2} (DCM)$ . The concentration of DCM is _________ ppm (by mass). Given : atomic mass : $C = 12$ $H = 1$ $Cl = 35.5$ density of $CHCl_{3} = 1.49 g cm^{- 3}$
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Answer: 148
Q892023 · 30 Jan 2023 · Shift 1· Numerical answer
The energy of one mole of photons of radiation of frequency $2 \times 1 0^{12} Hz$ in $J mol^{- 1}$ is ___________. (Nearest integer) $[Given : h = 6.626 \times 1 0^{- 34} Js$ $N_{A} = 6.022 \times 1 0^{23} mol^{- 1}]$
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Answer: 798
Q862023 · 29 Jan 2023 · Shift 1· Numerical answer
Solid Lead nitrate is dissolved in 1 litre of water. The solution was found to boil at $100.1 5^{\circ} C$ . 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 $PbC l_{2}$ formed is ____ $\times 1 0^{- 6}$ at 298 K. (Nearest integer) Given : $K_{b} = 0.5 K kg mo l^{- 1}$ and $K_{f} = 1.8 K kg mo l^{- 1}$ . Assume molality to be equal to molarity in all cases.
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Answer: 13
Q662023 · 29 Jan 2023 · Shift 2
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. $C_{9} H_{6}$
2. B. $C_{6} H_{6}$
3. C. $C_{8} H_{6}$
4. D. $C_{9} H_{9}$
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Answer: C
Q792023 · 29 Jan 2023 · Shift 2
The concentration of dissolved Oxygen in water for growth of fish should be more than $\underline{X}$ ppm and Biochemical Oxygen Demand in clean water should be less than $\underline{Y}$ ppm. X and Y in ppm are, respectively.
1. A. $X 4 Y 15$
2. B. $X 4 Y 8$
3. C. $X 6 Y 12$
4. D. $X 6 Y 5$
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Answer: D
Q822023 · 24 Jan 2023 · Shift 1· Numerical answer
When $F e_{0.93} O$ is heated in presence of oxygen, it converts to $F e_{2} O_{3}$ . The number of correct statement/s from the following is ____ A. The equivalent weight of $F e_{0.93} O$ is $\frac{Molecular weight}{0.79}$ B. The number of moles of $F e^{2 +}$ and $F e^{3 +}$ in 1 mole of $F e_{0.93} O$ is 0.79 and 0.14 respectively C. $F e_{0.93} O$ is metal deficient with lattice comprising of cubic closed packed arrangement of $O^{2 -}$ ions D. The % composition of $F e^{2 +}$ and $F e^{3 +}$ in $F e_{0.93} O$ is 85% and 15% respectively
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Answer: 4
Q852023 · 24 Jan 2023 · Shift 1· Numerical answer
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Answer: 2
Q822023 · 24 Jan 2023 · Shift 2· Numerical answer
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Answer: 620