For a first-order reaction A \(\rightarrow\) Products, initial concentration of A is 0.1 M, which becomes 0.001 M after 5 minutes. Rate constant for the reaction in min-1 is

1. 0.2303 2. 1.3818 
3. 0.9212 4. 0.4606
Subtopic:  First Order Reaction Kinetics |
 70%
From NCERT
NEET - 2022
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The half-life of a first-order reaction is 2000 years. If the concentration after 8000 years is 0.02 M, then the initial concentration was:
1. 0.16 M 2. 0.32 M
3. 0.08 M 4. 0.04 M
Subtopic:  First Order Reaction Kinetics |
 61%
From NCERT
NEET - 2022
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The rate constant for a first order reaction is 4.606×10-3 s-1. The time required to reduce 2.0 g of the reactant to 0.2 g is:

1. 200 s 2. 500 s
3. 1000 s 4. 100 s
Subtopic:  First Order Reaction Kinetics |
 82%
From NCERT
NEET - 2020
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If the rate constant for a first order reaction is k, the time (t) required for the completion of 99% of the reaction is given by:

1. t=2.303/k

2. t=0.693/k

3. t=6.909/k

4. t=4.606/k

Subtopic:  First Order Reaction Kinetics |
 59%
From NCERT
NEET - 2019
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A first-order reaction has a rate constant of 2.303×10-3 s-1. The time required for 40 g of this reactant to reduce to 10 g will be [Given that log102=0.3010]

1. 230.3 s

2. 301 s

3. 2000 s

4. 602 s

Subtopic:  First Order Reaction Kinetics |
 83%
From NCERT
NEET - 2019
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A first-order reaction has a specific reaction rate of
10-2 sec-1. How much time will it take for 20 g of the reactant to reduce to 5 g?

1. 138.6 sec 2. 346.5 sec
3. 693.0 sec 4. 238.6 sec
Subtopic:  First Order Reaction Kinetics |
 77%
From NCERT
NEET - 2017
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The rate of a first-order reaction is 0.04 mol l–1 s–1 at 10 seconds and 0.03 mol l–1 s–1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is:
1. 44.1 s

2. 54.1 s

3. 24.1 s

4. 34.1 s

Subtopic:  First Order Reaction Kinetics |
 61%
From NCERT
NEET - 2016
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In a zero-order reaction for every 10 ° rise of temperature, the rate is doubled.
If the temperature is increased from 10 °C to 100 °C,
the rate of the reaction will become:

1. 256 times

2. 512 times

3. 64 times

4. 128 times

Subtopic:  First Order Reaction Kinetics |
 84%
From NCERT
AIPMT - 2012
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The half-life of a certain enzyme catalysed reaction is 138 s, that follow the 1st order kinetics. The time required for the concentration of the substance to fall from 1.28 mg L–1 to 0.04 mg L–1, is:

1. 276 s 

2. 414 s

3. 552 s 

4. 690 s

Subtopic:  First Order Reaction Kinetics |
 73%
From NCERT
AIPMT - 2011
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The reaction of hydrogen and iodine monochloride is given as: 
H2(g) + 2ICl(g) → 2HCl(g) + I2(g
This reaction is of first order with respect to H2(g) and ICl(g), for which of the following proposed mechanisms:
Mechanism A: 
H2(g) + 2ICl(g) → 2HCl(g) + I2(g
Mechanism B: 
H2(g) + ICl(g) →HCl(g) + HI(g); slow 
HI(g) + ICl(g) →HCl(g) + I2(g); fast

1. B Only

2. A and B both

3. Neither A nor B

4. A only

Subtopic:  First Order Reaction Kinetics |
 63%
From NCERT
AIPMT - 2007
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