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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For the chemical reaction N2g+3H2g  2NH3g the correct option is:

1. 3dH2dt=2dNH3dt

2. -13dH2dt=-12dNH3dt

3. -dN2dt=2dNH3dt

4. -dN2dt=12dNH3dt

Subtopic:  Definition, Rate Constant, Rate Law |
 82%
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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For a reaction, activation energy Ea=0 and the rate constant at 200 K is    1.6 X 106s-1. The rate constant at 400K will be [Given that gas constant, R=8.314 J K-1 mol-1]

1.  3. 2 x 104 s-1
2. 1.6 x 106s-1

3. 1.6 x103 s-1

4. 3.2 x 106 s-1

Subtopic:  Arrhenius Equation |
 76%
From NCERT
NEET - 2019
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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 |
 81%
From NCERT
NEET - 2020
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An increase in the concentration of the reactants of a reaction leads to a change in:

1. heat of reaction

2. threshold energy

3. collision frequency

4. activation energy

Subtopic:  Arrhenius Equation |
 63%
From NCERT
NEET - 2020
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The half-life for a zero-order reaction having 0.02 M initial concentration of reactant is 100 s. The rate constant (in mol L-1 s-1) for the reaction is:

1. 1.0×10-4

2. 2.0×10-4

3. 2.0×10-3

4. 1.0×10-2

Subtopic:  Order, Molecularity and Mechanism |
 74%
From NCERT
NEET - 2020
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What does ZAB represent in the collision theory of chemical reactions?

1. The fraction of molecules with energies greater than Ea

2. The collision frequency of reactants, A and B

3. Steric factor

4. The fraction of molecules with energies equal to Ea

Subtopic:  Arrhenius Equation |
 69%
From NCERT
NEET - 2020
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For a reaction AB, enthalpy of reaction is -4.2 kJmol-1 and enthalpy of activation is 9.6 kJmol-1. The correct potential energy profile for the reaction is:

1. 2.
3. 4.
Subtopic:  Arrhenius Equation |
 70%
From NCERT
NEET - 2021
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The slope of Arrhenius Plot (ln k v/s 1T) of the first-order reaction is -5×103 K. The value of Ea of the reaction is:

[Given R = 8.314 JK-1 mol-1]

1. 166 kJ mol-1 2. -83 kJ mol-1
3. 41.5 kJ mol-1 4. 83.0 kJ mol-1
Subtopic:  Arrhenius Equation |
 71%
From NCERT
NEET - 2021
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