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A first order reaction is completed 90% in 90 minutes. Hence, the time required to complete 50% of the reaction is approximately how many minutes?

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Important Questions on Chemical Kinetics

MEDIUM
The rate constant for the first order reaction is 60 s-1. How much time will it take to reduce the concentration of the reactant to 116 th value?
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For a zero - order reaction with rate constant k, the slope of the plot reactant concentration against time is
HARD
The half-life period of a first-order reaction is 15 minutes. The amount of substance left after one hour will be
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The rate of a first-order reaction is 0.04 mol l-1s-1 at 10 second and 0.03 mol l-1s-1 at 20 seconds after initiation of the reaction. The half-life period of the reaction is:
EASY
If 50 % of a reaction occurs in 100 second and 75 % of the reaction occurs in 200 second, the order of this reaction is:
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Decomposition of H2O2 follows a first order reaction. In fifty minutes the concentration of H 2 O 2 decreases from 0.5 to 0.125 M in one such decomposition. When the concentration of H2O2 reaches 0.05 M , the rate of formation of O2 will be:
EASY
A first-order reaction has a specific reaction rate 10-2sec-1. How much time will it take for 20 g the reactant to reduce to 5 g?
HARD

The decomposition reaction 2N2O5g  2N2O4g+O2g is started in a closed cylinder under the isothermal isochoric condition at an initial pressure of 1 atm. After Y10×103 s , the pressure inside the cylinder is found to be 1.45 atm . If the rate constant of the reaction is 5×10-4s-1, assuming ideal gas behaviour, the value of Y is(nearest integer)

EASY
It takes 1h for a first order reaction to go to 50% completion. The total time required for the same reaction to reach 87.5%  completion will be
EASY
The rate constant for a first order reaction is 7.0×10-4 s-1. If initial concentration of the reactant is 0.080 M, what is the half-life of the reaction?
MEDIUM
During the nuclear explosion, one of the products is 90Sr with half life of 6.93 years. If 1μg of 90Sr was absorbed in the bones of a newly born baby in place of Ca, how much time, in years, is required to reduce it by 90% if it is not lost metabolically ____________.
HARD
The reaction 2N2O5g4NO2g+O2(g) follows first order kinetics. The pressure of a vessel containing only N2O5 was found to increase from 50 mm Hg to 87.5 mm Hg in 30 min. The pressure exerted by the gases after 60 min. Will be (Assume temperature remains constant) :
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The given plots represent the variation of the concentration of a reactant R with time for two different reactions (i) and (ii). The respective orders of the reaction are
(i) Question Image

(ii) Question Image

EASY
Decomposition of X exhibits a rate constant of 0.05μg/year. How many years are required for the decomposition of 5μg of X into 2.5μg?
MEDIUM
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
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The rate constant of a first order reaction is 231×10-5 s-1. How long will 4 g of this reactant reduce to 2 g?
EASY
Under what condition the order of the reaction,

2HIH2g+I2g, is zero
EASY
When initial concentration of a reactant is doubled in a reaction, its half-life period is not affected. The order of the reaction is:
EASY
The rate constant of the reaction AB is 0.6×10-3 mole per liter per second. If the initial concentration of A is 5 M, then the concentration of B after 20 minutes is: