Chemical Kinetics

If the half-life (t1/2) for a first order reaction is 1 minute, then the time required for 99.9\% completion of the reaction is closest to :

1. 5 minutes
2. 10 minutes
3. 2 minutes
4. 4 minutes

The given graph is a representation of kinetics of a reaction [figure] The y and x axes for zero and first order reactions, respectively are

1. zero order (y = concentration and x = time), first order (y = t1/2 and x = concentration)
2. zero order (y = concentration and x = time), first order (y = rate constant and x = concentration)
3. zero order (y = rate and x = concentration), first order (y = t1/2 and x = concentration)
4. zero order (y = rate and x = concentration), first order (y = rate and x = t1/2)

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. 0.04 M
2. 0.16 M
3. 0.32 M
4. 0.08 M

The correct difference between first and second order reactions is that

1. the rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations
2. the half-life of a first-order reaction does not depend on [A]0; the half-life of a second order reaction does depend on [A]0
3. a first-order reaction can be catalysed; a second-order reaction cannot be catalysed
4. the rate of a first-order reaction does depend on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations

When initial concentration of the reactant is doubled, the half-life period of a zero order reaction

1. is halved
2. is doubled
3. is tripled
4. remains unchanged.

When initial concentration of a reactant is doubled in a reaction, its half-life period is not affected. The order of the reaction is

1. second
2. more than zero but less than first
3. zero
4. first.

A reaction is 50\% complete in 2 hours and 75\% complete in 4 hours. The order of reaction is

1. 1
2. 2
3. 3
4. 0

The half-life of a substance in a certain enzyme-catalysed reaction is 138 s. 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. 414 s
2. 552 s
3. 690 s
4. 276 s

Half-life period of a first order reaction is 1386 s. The specific rate constant of the reaction is

1. 0.5 10-2 s-1
2. 0.5 10-3 s-1
3. 5.0 10-2 s-1
4. 5.0 10-3 s-1

In a first-order reaction A B, if k is rate constant and initial concentration of the reactant A is 0.5 M, then the half-life is

1. 2k
2. 2k 0.5
3. 2k
4. 0.6930.5k

For a first order reaction A B the reaction rate at reactant concentration of 0.01 M is found to be 2.0 10-5 mol L-1 s-1. The half-life period of the reaction is

1. 30 s
2. 220 s
3. 300 s
4. 347 s

The rate of a first order reaction is 1.5 10-2 mol L-1 min-1 at 0.5 M concentration of the reactant. The half-life of the reaction is

1. 0.383 min
2. 23.1 min
3. 8.73 min
4. 7.53 min

The radioisotope, tritium (13H) has a half-life of 12.3 years. If the initial amount of tritium is 32 mg, how many milligrams of it would remain after 49.2 years?

1. 1 mg
2. 2 mg
3. 4 mg
4. 8 mg

A human body required 0.01 m activity of radioactive substance after 24 hours. Half life of radioactive substance is 6 hours. Then injection of maximum activity of radioactive substance that can be injected is

1. 0.08
2. 0.04
3. 0.16
4. 0.32

A 300 g radioactive sample has a half-life of 3 hours. After 18 hours, the remaining quantity is

1. 4.68 g
2. 2.34 g
3. 3.34 g
4. 9.37 g