Chemical Kinetics · JEE Main previous year questions

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2023 19 questions

Q832023 · 13 Apr 2023 · Shift 1· Numerical answer
$t_{87.5}$ is the time required for the reaction to undergo $87.5%$ completion and $t_{50}$ is the time required for the reaction to undergo $50%$ completion. The relation between $t_{87.5}$ and $t_{50}$ for a first order reaction is $t_{87.5} = x \times t_{50}$ The value of $x$ is ___________. (Nearest integer)
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Answer: 3
Q812023 · 13 Apr 2023 · Shift 2· Numerical answer
$A (g) \to 2 B (g) + C (g)$ is a first order reaction. The initial pressure of the system was found to be $800 mm Hg$ which increased to $1600 mm Hg$ after $10 min$ . The total pressure of the system after $30 min$ will be ___________ mm Hg. (Nearest integer)
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Answer: 2200
Q872023 · 12 Apr 2023 · Shift 1· Numerical answer
The reaction $2 NO + Br_{2} \to 2 NOBr$ takes places through the mechanism given below: $NO + Br_{2} ⇌ NOBr_{2} (fast)$ $NOBr_{2} + NO \to 2 NOBr (slow)$ The overall order of the reaction is __________.
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Answer: 3
Q862023 · 10 Apr 2023 · Shift 1· Numerical answer
A molecule undergoes two independent first order reactions whose respective half lives are 12 min and 3 min. If both the reactions are occurring then the time taken for the 50% consumption of the reactant is ___________ min. (Nearest integer)
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Answer: 2
Q852023 · 10 Apr 2023 · Shift 2· Numerical answer
The number of incorrect statement/s from the following is _________ A. The successive half lives of zero order reactions decreases with time. B. A substance appearing as reactant in the chemical equation may not affect the rate of reaction C. Order and molecularity of a chemical reaction can be a fractional number D. The rate constant units of zero and second order reaction are $mol L^{- 1} s^{- 1}$ and $mol^{- 1} L s^{- 1}$ respectively
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Answer: 1
Q812023 · 8 Apr 2023 · Shift 1· Numerical answer
The number of given statement/s which is/are correct is __________. (A) The stronger the temperature dependence of the rate constant, the higher is the activation energy. (B) If a reaction has zero activation energy, its rate is independent of temperature. (C) The stronger the temperature dependence of the rate constant, the smaller is the activation energy. (D) If there is no correlation between the temperature and the rate constant then it means that the reaction has negative activation energy.
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Answer: 2
Q902023 · 6 Apr 2023 · Shift 1· Numerical answer
For the adsorption of hydrogen on platinum, the activation energy is $30 k Jmol^{- 1}$ and for the adsorption of hydrogen on nickel, the activation energy is $41.4 k Jmol^{- 1}$ . The logarithm of the ratio of the rates of chemisorption on equal areas of the metals at $300 K$ is ________ (Nearest integer) Given: $ln 10 = 2.3$ $R = 8.3 J K^{- 1} mol^{- 1}$
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Answer: 2
Q842023 · 1 Feb 2023 · Shift 1· Numerical answer
A and B are two substances undergoing radioactive decay in a container. The half life of A is 15 min and that of B is 5 min. If the initial concentration of B is 4 times that of A and they both start decaying at the same time, how much time will it take for the concentration of both of them to be same? _____________ min.
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Answer: 15
Q882023 · 31 Jan 2023 · Shift 1· Numerical answer
$A \to B$ The rate constants of the above reaction at $200 K$ and $300 K$ are $0.03 min^{- 1}$ and $0.05 min^{- 1}$ respectively. The activation energy for the reaction is ___________ $J$ (Nearest integer) (Given : $ln 10 = 2.3$ $R = 8.3 J K^{- 1} mol^{- 1}$ $lo g 5 = 0.70$ $lo g 3 = 0.48$ $lo g 2 = 0.30$ )
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Answer: 2520
Q892023 · 31 Jan 2023 · Shift 2· Numerical answer
The rate constant for a first order reaction is $20 min^{- 1}$ . The time required for the initial concentration of the reactant to reduce to its $\frac{1}{32}$ level is ___________ $\times 1 0^{- 2} min$ . (Nearest integer) (Given : $ln 10 = 2.303$ and $lo g 2 = 0.3010$ )
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Answer: 17
Q822023 · 30 Jan 2023 · Shift 1· Numerical answer
If compound A reacts with B following first order kinetics with rate constant $2.011 \times 1 0^{- 3} s^{- 1}$ . The time taken by A (in seconds) to reduce from $7 g$ to $2 g$ will be ___________. (Nearest Integer) $[lo g 5 = 0.698, lo g 7 = 0.845, lo g 2 = 0.301]$
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Answer: 623
Q832023 · 29 Jan 2023 · Shift 1· Numerical answer
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Answer: 1
Q882023 · 29 Jan 2023 · Shift 2· Numerical answer
For conversion of compound $A \to B$ , the rate constant of the reaction was found to be $4.6 \times 1 0^{- 5} L mo l^{- 1} s^{- 1}$ . The order of the reaction is ____.
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Answer: 2
Q782023 · 25 Jan 2023 · Shift 1
1. A.(a)
2. B.(b)
3. C.(d)
4. D.(c)
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Answer: D
Q892023 · 25 Jan 2023 · Shift 1· Numerical answer
For the first order reaction $A \to B$ , the half life is 30 min. The time taken for 75% completion of the reaction is ____ min. (Nearest integer) Given : log 2 = 0.3010 log 3 = 0.4771 log 5 = 0.6989
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Answer: 60
Q832023 · 25 Jan 2023 · Shift 2· Numerical answer
A first order reaction has the rate constant, $k = 4.6 \times 1 0^{- 3} s^{- 1}$ . The number of correct statement/s from the following is/are ____ Given : $lo g 3 = 0.48$ A. Reaction completes in 1000 s. B. The reaction has a half-life of 500 s. C. The time required for 10% completion is 25 times the time required for 90% completion. D. The degree of dissociation is equal to $(1 - e^{- kt})$ E. The rate and the rate constant have the same unit.
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Answer: 1
Q862023 · 24 Jan 2023 · Shift 1· Numerical answer
The number of correct statement/s from the following is ____ A. Larger the activation energy, smaller is the value of the rate constant. B. The higher is the activation energy, higher is the value of the temperature coefficient. C. At lower temperatures, increase in temperature causes more change in the value of k than at higher temperature D. A plot of $ln k$ vs $\frac{1}{T}$ is a straight line with slope equal to $- \frac{E _{a}}{R}$
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Answer: 3
Q692023 · 24 Jan 2023 · Shift 2
A student has studied the decomposition of a gas $A B_{3}$ at $2 5^{\circ} C$ . He obtained the following data. $p (mm Hg) relative t_{1/2} (s) 50410022001 400 0.5$ The order of the reaction is
1. A.2
2. B.0.5
3. C.1
4. D.0 (zero)
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Answer: A
Q892023 · 24 Jan 2023 · Shift 2· Numerical answer
The number of statement/s which are the characteristics of physisorption is __________ A. It is highly specific in nature B. Enthalpy of adsorption is high C. It decreases with increase in temperature D. It results into unimolecular layer E. No activation energy is needed
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Answer: 2