Revisal Problems (Past 13 Years) JEE Main (Chemical Kinetics) - JEE MCQ

A radioactive substance decays 20% in 10 min. If at the start, there are 5 x 10²⁰ atoms present, after what time will the number of atoms be reduced to 5 x 10¹⁷ atoms?

Rate constant of a reaction with a virus is 3.3 x 10^-4 s^-1. Time required for a virus to become 75% inactivated is 

For the first order reaction,   total pressure is 350 mm after 30 min and 500 mm after complete reaction. Thus, rate constant is

t_1/A can be taken as the time taken for the concentration of a reactant to drop to 3/4 of the initial value. If the rate constant for a first order reaction is k, then t _1/4 can be written as 

For the following first order gaseous phase reaction,

time taken for acetone vapour pressure to drop to 0.30 atm from 2 atm is 

The rate constant for a first order reaction is 60 s^-1. How much time will it take to reduce the initialconcentration of the reactant to its (1/16)th value?

The half-life of a reaction was doubled when initial concentration was doubled. Thus, order of the reaction is

Rate law of the reaction A → product is

rate = k[A]

Graphically, it is represented as

Hence, rate constant is 

For the non-stoichiometric reaction, the following kinetic data were obtained in three separate experiments, all at 298 K.

Q. 

The rate law for the formation of C is

A hydrogenation reaction is carried out at 500 K.

Q. 

If rate remains constant, then E_a is 

Rate of a particular reaction increases by a factor 2 when the temperature is increased from 27°C to 37°C. Hence, activation energy of the reaction is

Interconversion of boat form to chair form of cyclohexane is first order (in both sides).

Equilibrium constant, Kc =10⁴

Also, energy of activation of conversion of chair to boat form is 42 kJ mol-¹ in the following equation

Q.

Observed reaction rate constant at 298 K is 

In the reaction, 

if we start with [A]₀ = 10 M , then after one natural life time, concentration of A decrea sed to 

Number of natural life times (T_av ) required for a first order reaction to achieve 99.9% level of completion is

For the reaction, 

rate law is 

Q.

At the start, pressure is 100 mm and after 10 min, pressure is 120 mm. Thus, rate constant (in min^-1) is

Q. 

HA and HB are two strong acids. Relative strength of strong acids is

Initial concentration of A = 2M and after 10 min, reaction is 10% completed. Thus, half-life period is

The decomposition of N₂O to N₂ and O₂ follow s rate law in gaseous phase as

Q. 

At 1000 K, half-life of the reaction is 3.58 x 10³ min. Starting with initial pressure of N₂O as 2.20 atm, total pressure after one half-life is

The rate of a first order reaction is 0.04 mol L^-1 s^-1 at 10 min and 0.03 mol L^-1 s^-1 at 20 min. Thus , half-life of the reaction is 

For the non-equilibrium process,

the rate is first order w.r.t. A and second order w.r.t. B.
When [A]= 1.0 M, [B]= 1.0 M, rate = 1.0x 10^-2 M s^-1

When 50% of each of reactant has been converted into products, rate is

For a reaction of the type 

[X]₀ is the concentration of X at time t = 0 and [X] is the concentration of X at time t = t

Thus, correct rate expression is

Direction (Q. Nos. 25-27) This section is based on Statement I and Statement II. Select the correct answer from the codes given below.

Q. 

Statement I : The rate of chemical reaction generally increases rapidly for a small temperature increase.

Statement II : Increase in temperature increases fraction of molecules with energies in excess of activation energy.

Statement I : For a certain reaction, large fraction of molecules has energy more than the threshold energy,yet the rate of reaction is very slow.

Statement II : Collisions are only effective if they have proper orientation. In the absence of proper orientation rate becomes, slow.

Statement I : Certain reactions are thermodynamically feasible but their rates are very slow.

Statement II : Energy of activation may be high for such reactions.