Chemical Kinetics · JEE Main previous year questions

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2024 15 questions

Q862024 · 9 Apr 2024 · Shift 1· Numerical answer
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Answer: 8
Q862024 · 9 Apr 2024 · Shift 2· Numerical answer
Consider the following first order gas phase reaction at constant temperature $A (g) \to 2B (g) + C (g)$ If the total pressure of the gases is found to be $200 torr$ after $23 sec$ . and $300 torr$ upon the complete decomposition of A after a very long time, then the rate constant of the given reaction is ____ $\times 1 0^{- 2} s^{- 1}$ (nearest integer) [Given : $lo g_{10} (2) = 0.301$ ]
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Answer: 3
Q822024 · 8 Apr 2024 · Shift 1· Numerical answer
Consider the following reaction $A + B \to C$ The time taken for A to become $1/ 4^{th}$ of its initial concentration is twice the time taken to become $1/2$ of the same. Also, when the change of concentration of B is plotted against time, the resulting graph gives a straight line with a negative slope and a positive intercept on the concentration axis. The overall order of the reaction is ____.
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Answer: 1
Q862024 · 6 Apr 2024 · Shift 2· Numerical answer
Consider the two different first order reactions given below $A + B \to C$ (Reaction 1) $P \to Q$ (Reaction 2) The ratio of the half life of Reaction 1 : Reaction 2 is $5 : 2$ If $t_{1}$ and $t_{2}$ represent the time taken to complete $2/ 3^{rd}$ and $4/ 5^{th}$ of Reaction 1 and Reaction 2 , respectively, then the value of the ratio $t_{1} : t_{2}$ is ________ $\times 1 0^{- 1}$ (nearest integer). [Given : $lo g_{10} (3) = 0.477$ and $lo g_{10} (5) = 0.699$ ]
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Answer: 17
Q852024 · 5 Apr 2024 · Shift 2· Numerical answer
Consider the following single step reaction in gas phase at constant temperature. $2 A_{(g)} + B_{(g)} \to C_{(g)}$ The initial rate of the reaction is recorded as $r_{1}$ when the reaction starts with $1.5 atm$ pressure of A and $0.7 atm$ pressure of B. After some time, the rate $r_{2}$ is recorded when the pressure of C becomes $0.5 atm$ . The ratio $r_{1} : r_{2}$ is ____ $\times 1 0^{- 1}$ . (Nearest integer)
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Answer: 315
Q832024 · 4 Apr 2024 · Shift 1· Numerical answer
Consider the following transformation involving first order elementary reaction in each step at constant temperature as shown below. $A + B Step 3 ⇌ Step 1 C Step 2 P$ Some details of the above reactions are listed below. $Step 123 Rate constant (sec^{- 1}) k_{1} k_{2} k_{3} Activation energy (kJ mol^{- 1}) 300200 E a_{3}$ If the overall rate constant of the above transformation (k) is given as $k = \frac{k _{1} k _{2}}{k _{3}}$ and the overall activation energy ( $E_{a}$ ) is $400 kJ mo l^{- 1}$ , then the value of $E a_{3}$ is ____ $kJ mo l^{- 1}$ (nearest integer)
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Answer: 100
Q862024 · 4 Apr 2024 · Shift 2· Numerical answer
Consider the following reaction, the rate expression of which is given below $A + B \to C$ $rate = k [A]^{1/2} [B]^{1/2}$ The reaction is initiated by taking $1 M$ concentration of A and B each. If the rate constant ( $k$ ) is $4.6 \times 1 0^{- 2} s^{- 1}$ , then the time taken for A to become $0.1 M$ is ________ sec. (nearest integer)
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Answer: 50
Q902024 · 1 Feb 2024 · Shift 1· Numerical answer
The ratio of $\frac{^{14} C}{^{12} C}$ in a piece of wood is $\frac{1}{8}$ part that of atmosphere. If half life of $^{14} C$ is $5730 years$ , the age of wood sample is ________ years.
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Answer: 17190
Q842024 · 1 Feb 2024 · Shift 2· Numerical answer
The following data were obtained during the first order thermal decomposition of a gas A at constant volume : $A (g) \to 2B (g) + C (g)$ | S.No. | Time /s | Total pressure /(atm) | | :--- | :--- | :--- | | 1. | 0 | 0.1 | | 2. | 115 | 0.28 | The rate constant of the reaction is ________ $\times 1 0^{- 2} s^{- 1}$ (nearest integer)
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Answer: 2
Q712024 · 31 Jan 2024 · Shift 1
Integrated rate law equation for a first order gas phase reaction is given by (where $P_{i}$ is initial pressure and $P_{t}$ is total pressure at time $t$ ) (Take the reaction to be of the type $A (g) \to B (g) + C (g)$ .)
1. A. $k = \frac{2.303}{t} \times lo g \frac{P _{i}}{( 2 P _{i} - P _{t} )}$
2. B. $k = \frac{2.303}{t} \times lo g \frac{( 2 P _{i} - P _{t} )}{P _{i}}$
3. C. $k = \frac{2.303}{t} \times \frac{P _{i}}{( 2 P _{i} - P _{t} )}$
4. D. $k = \frac{2.303}{t} \times lo g \frac{2 P _{i}}{( 2 P _{i} - P _{t} )}$
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Answer: A
Q882024 · 30 Jan 2024 · Shift 1· Numerical answer
The rate of a first order reaction is $0.04 mol L^{- 1} s^{- 1}$ at 10 minutes and $0.03 mol L^{- 1} s^{- 1}$ at 20 minutes after initiation. Half life of the reaction is _________ minutes. (Given $lo g 2 = 0.3010, lo g 3 = 0.4771$ )
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Answer: 24
Q862024 · 29 Jan 2024 · Shift 1· Numerical answer
For a reaction taking place in three steps at same temperature, overall rate constant $K = \frac{K _{1} K _{2}}{K _{3}}$ . If $E a_{1}, E a_{2}$ and $E a_{3}$ are 40, 50 and $60 kJ/mol$ respectively, the overall Ea is _________ $kJ/mol$ .
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Answer: 30
Q872024 · 29 Jan 2024 · Shift 2· Numerical answer
The half-life of radioisotope bromine - 82 is 36 hours. The fraction which remains after one day is _________ $\times 1 0^{- 2}$ . (Given antilog $0.2006 = 1.587$ )
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Answer: 63
Q822024 · 27 Jan 2024 · Shift 1· Numerical answer
Consider the following data for the given reaction $2 HI_{(g)} \to H_{2 (g)} + I_{2 (g)}$ | | 1 | 2 | 3 | | :--- | :--- | :--- | :--- | | $HI (mol L^{- 1})$ | $0.005$ | $0.01$ | $0.02$ | | $Rate (mol L^{- 1} s^{- 1})$ | $7.5 \times 1 0^{- 4}$ | $3.0 \times 1 0^{- 3}$ | $1.2 \times 1 0^{- 2}$ | The order of the reaction is ________.
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Answer: 2
Q842024 · 27 Jan 2024 · Shift 2· Numerical answer
Time required for completion of $99.9%$ of a First order reaction is _______ times of half life ( $t_{1/2}$ ) of the reaction.
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Answer: 10