# Consider the reaction, 2A + B → Products. When concentration of B alone was doubled, the half-life did not change. When the concentration of A alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is: 1. L mol–1 s–1 2. no unit 3. mol L–1s–1 4. s–1

Subtopic:  Order, Molecularity and Mechanism |
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The rate equation for the reaction 2A+B→C is found to be:
rate = k [A] [B]
The correct statement in relation to this reaction is that the:

 1 Unit of k must be s-1 2 t1/2 is a constant 3 Rate of formation of C is twice the rate of disappearance of A 4 Value of k is independent of the initial concentrations of A and B
Subtopic:  Definition, Rate Constant, Rate Law |
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The time for the half-life period of a certain reaction A → Products is 1 hour. When the initial concentration of the reactant 'A' is 2.0 mol L-1, the time taken for its concentration to come from 0.50 to 0.25 mol L-1,if it is a zero-order reaction, is:

1. 1h

2. 4 h

3. 0.5 h

4. 0.25 h

Subtopic:  Order, Molecularity and Mechanism |
66%
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For the non – stoichiometry reaction 2A + B → C + D, the following kinetic data were obtained in three separate experiments (all at 298 K).

 Initial Concentration (A) Initial Concentration (B) Initial rate of formation of C (mol L– S–) 0.1 M 0.1 M 0.2 M 0.1 M 0.2 M 0.1 M 1.2 × 10–3 1.2 × 10–3 2.4 × 10–3

The rate law for the formation of C is:

1. $\frac{\mathrm{dc}}{\mathrm{dt}}=\mathrm{k}\left[\mathrm{A}{\right]}^{2}\left[\mathrm{B}\right]$

2. $\frac{\mathrm{dc}}{\mathrm{dt}}=\mathrm{k}\left[\mathrm{A}\right]\left[\mathrm{B}{\right]}^{2}$

3. $\frac{\mathrm{dc}}{\mathrm{dt}}=\mathrm{k}\left[\mathrm{A}\right]$

4. $\frac{\mathrm{dc}}{\mathrm{dt}}=\mathrm{k}\left[\mathrm{A}\right]\left[\mathrm{B}\right]$

Subtopic:  Order, Molecularity and Mechanism |
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The rate of a reaction is decreased by 3.555 times when the temperature was changed from 40°C to 30°C. The activation energy (in kJ ${\mathrm{mol}}^{-1}$) of the reaction is:
(Take R=8.314 J  In 3.555=1.268)

1. 100 kJ/mol
2. 120 kJ/mol
3. 95 kJ/mol
4. 108 kJ/mol

Subtopic:  Arrhenius Equation |
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If 75 % of a first-order reaction was completed in 90 minutes, 60 % of the same reaction would be completed in approximately (in minutes):

(Take : log 2 = 0.30 ; log 2.5 = 0.40)

1. 50 min

2. 60 min

3. 70 min

4. 65 min

Subtopic:  First Order Reaction Kinetics |
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In a first order reaction, time required for completion of 99.9% is X times of half-life (t1/2) of the reaction. When reaction is completed 99.9%, [R]n = [R]0 – 0.999[R]0 .The value of X is-

1. 5
2. 10
3. 15
4. 20

Subtopic:  First Order Reaction Kinetics |
80%
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The decomposition of N2O5 in CCl4 at 318K has been studied by monitoring the concentration of N2O5 in the solution. Initially, the concentration of N2O5 is 2.33 mol L–1 and after 184 minutes, it is reduced to 2.08 mol L–1. The reaction takes place according to the equation

2 N2O5 (g)  4 NO2 (g) + O2 (g)

The rate of production of NO2 during this period is-

1. 5.72 × 10
–3 mol L–1 min–1
2. 2.72 × 10
–3 mol L–1 min–1
3. 1.72 × 10
–5 mol L–1 min–1
4. 6.72 × 10
–4 mol L–1 min–1

Subtopic:  Definition, Rate Constant, Rate Law |
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Half-life of substance A following first order kinetics is 5 days. Starting with 100g of A, the amount left after 15 days will be:

1.  25 g

2. 50 g

3. 12.5 g

4. 6.25 g

Subtopic:  First Order Reaction Kinetics |
86%
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H2 gas is absorbed on the metal surface like gold, tungsten, etc. This follows ________ order reaction:

1. Third

2. Second

3. Zero

4. First

Subtopic:  Order, Molecularity and Mechanism |
68%
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