All Exams  >   NEET  >   Chemistry CUET UG Mock Test Series 2026  >   All Questions

All questions of Chemical Kinetics for NEET Exam

Half-life period of a second order reaction is
a) independent of the concentration
b) inversaly proportional to the initial conc
c) inversely proportional to conc.
d) directly proportional to the conc.
The answer is b.

Dr Manju Sen answered
The correct answer is Option B.
 
Relation between half-life period of a reaction and initial concentration is as follows: 
For first order reaction         (Half life α a0 )
For second order reaction    (Half life ∝ 
1/a)
For third order reaction         (Half life ∝ 1a2)

For a reaction,
 
hen x, y and z are 
  • a)
    1:1:1
  • b)
    3:2:3
  • c)
    3:3:2
  • d)
    2:2:3
Correct answer is option 'C'. Can you explain this answer?

Divey Sethi answered
For the reaction: xA + yB → zC

Given that,

Multiplying equation 2 by 1/3, we get

On comparing equation 1 and 3,
x = 3, y = 3, z = 2.

For a chemical reaction the rate constant is nearly doubled with the rise in temperature by
a)100ºC
b)10ºC
c)50ºC
d)273ºC
Correct answer is option 'B'. Can you explain this answer?

Rohit Shah answered
It has been found that rate constant is nearly doubled for a chemical reaction with a rise in temperature by 10deg. We can explain the dependence of the rate of a chemical reaction on temperature by Arrhenius equation.
Payal Sapra answered
Hi tausif. ...let dr/dt is proportional to [A]^n is equation 1st.... then 1/2 dr/dt is prportional to [2A]^n.....equation 2nd compare both equations...u'll get 2^n is equal to 1/2....so we get n is equal to minus 1..... hope u get it

The time for half life period of a certain reaction A → Products is 1 h. When the initial concentration of the reactant 'A' is 2.0 mol L–1, how much time does it take for its concentration to come from 0.50 to 0.25 mol L–1, if it is a zero order reaction?
  • a)
    0.25 h
  • b)
    1 h
  • c)
    4 h
  • d)
    0.5 h
Correct answer is option 'A'. Can you explain this answer?

Shashi Kumar answered
For a zero order reaction,
(T)half = Initial concentration/ 2× reaction constant
from this equation find out k.
also another formula for zero order reaction-
(A)t =(A)o - KT
put the value of k , (A)t=0.25 and (A)o= 0.50
you will get the answer.

The effect of temperature on reaction rate is given by
  • a)
    Arrhenius equation
  • b)
    Kirchoff’s Equation
  • c)
    Clauius Claperyron equation
  • d)
    Gibb’s Helmholtz equation
Correct answer is option 'A'. Can you explain this answer?

Effect of Temperature on Reaction Rate - Arrhenius Equation

The Arrhenius equation explains the effect of temperature on the reaction rate. It is a mathematical formula that relates the rate constant of a chemical reaction to the temperature and activation energy of the reaction.

The equation is given by:

k = A * e^(-Ea/RT)

Where,
k - rate constant
A - pre-exponential factor
Ea - activation energy
R - gas constant
T - temperature

Explanation of the Equation:

Pre-Exponential Factor (A): It is a constant that reflects the frequency at which reactant molecules collide with each other. A higher value of A means that more collisions occur, thus increasing the reaction rate.

Activation Energy (Ea): It is the minimum energy required to initiate a chemical reaction. A higher value of Ea means that more energy is required to initiate the reaction, thus decreasing the reaction rate.

Gas Constant (R): It is a constant that relates the energy of a system to its temperature.

Temperature (T): It is the measure of the average kinetic energy of the molecules in a system. As the temperature increases, the kinetic energy of the molecules increases, leading to more collisions and thus increasing the reaction rate.

Application of the Equation:

The Arrhenius equation is widely used in chemical kinetics to predict the effect of temperature on the reaction rate. It is also used to determine the activation energy of a reaction by measuring the rate constant at different temperatures.

Conclusion:

In conclusion, the Arrhenius equation is a useful tool to understand the effect of temperature on the reaction rate. It helps in predicting the rate of a chemical reaction at different temperatures and determining the activation energy of a reaction.

The rate of a chemical reaction doubles for every 10°C rise of temperature. If the temperature is raised by 50°C, the rate of the reaction increases by about
  • a)
    64 times
  • b)
    10 times
  • c)
    24 times
  • d)
    32 times
Correct answer is option 'D'. Can you explain this answer?

Mohit Rajpoot answered
For every 10°C rise of temperature, the rate is doubled. Thus, the temperature coefficient of the reaction = 2
When temperature is increased by 50°, rate becomes
=2(50/10) = 25 times = 32 times

Direction (Q. Nos. 1-13) This section contains multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE is correct
Q. In the following reaction, which has maximum rate w.r.t. rate of disappearance of NH3?
4NH3 + 50  4NO + 6H2O
  • a)
    O2
  • b)
    NO
  • c)
    H2O
  • d)
    Equal
Correct answer is option 'C'. Can you explain this answer?

Nabanita Basu answered
Understanding the Reaction
The given reaction is:
4NH3 + 5O2 → 4NO + 6H2O
This reaction involves the disappearance of ammonia (NH3) and the appearance of the products NO and H2O.
Rate of Reaction
The rate of a chemical reaction can be expressed in terms of the rate of disappearance of reactants or the rate of appearance of products.
Stoichiometry of the Reaction
- According to the stoichiometry:
- 4 moles of NH3 produce 4 moles of NO and 6 moles of H2O.
- The coefficients in the balanced equation indicate the relative rates of disappearance and appearance.
Rate of Disappearance
- The rate of disappearance of NH3 is given by:
Rate = - (1/4) * d[NH3]/dt
- The rates for O2, NO, and H2O can be expressed similarly:
- O2: Rate = - (1/5) * d[O2]/dt
- NO: Rate = (1/4) * d[NO]/dt
- H2O: Rate = (1/6) * d[H2O]/dt
Comparison of Rates
To find the maximum rate of disappearance, we can compare the rates derived from the balanced equation:
- NH3: - (1/4) (for every 1 mole of disappearance)
- O2: - (1/5) (for every 1 mole of disappearance)
- NO: (1/4) (for every 1 mole of appearance)
- H2O: (1/6) (for every 1 mole of appearance)
The fractions reveal how many moles of each substance are involved in the reaction. The lower the denominator, the higher the rate of disappearance or appearance.
Conclusion
- Among the reactants and products, H2O has the highest coefficient when considering the rate of disappearance of NH3.
- Therefore, the maximum rate of disappearance is related to H2O's formation.
Thus, the correct answer is option 'C' (H2O).

Reaction kinetics deals with the study of
  • a)
    Rate of reaction
  • b)
    Mechanism of reaction
  • c)
    Factors which affects the rate of reaction
  • d)
    All of the mentioned
Correct answer is option 'D'. Can you explain this answer?

Om Desai answered
Reaction kinetics deals with the study of rate of reaction, their mechanism and the factors which affects the rate of reaction. It specifies all the general characteristics of a chemical reaction.

The unit of rate constant for a first order reaction is
  • a)
    Mol/L
  • b)
    Mol2 / L2 / S2
  • c)
    S-1
  • d)
    Mol/L/S
Correct answer is option 'C'. Can you explain this answer?

Nikita Singh answered
The correct answer is Option C.
Let R be the rate of reaction.
For first order reaction,
R=K[A]1
⇒K=R[A]-1
Whereas, K and [A] are rate constant and initial concentration of reactant respectively.
Therefore,
Unit of rate constant =(mol L-1)1-nsec-1
For first order reaction, n=1
Unit of rate constant = sec-1
Hence the unit of rate constant for first order reaction is sec-1.

If a reaction proceeds with a uniform rate throughout, the reaction is
  • a)
    Third order
  • b)
    Second order
  • c)
    First order
  • d)
    Zero order
Correct answer is option 'D'. Can you explain this answer?

Roshni Chavan answered
Reaction Rate and Order:

The rate of a chemical reaction refers to how quickly reactants are consumed and products are formed. It is determined by the rate equation, which shows how the concentration of reactants influences the rate of the reaction. The order of a reaction refers to the power to which the concentration of a reactant is raised in the rate equation.

Uniform Rate throughout the Reaction:

When a reaction proceeds with a uniform rate throughout, it means that the rate of the reaction remains constant over time. This implies that the concentration of the reactants does not affect the reaction rate. In other words, the reaction is not dependent on the concentration of the reactants.

Zero Order Reaction:

When the reaction rate is independent of the concentration of the reactants, it is referred to as a zero order reaction. In this case, the rate equation is expressed as:

Rate = k

where k is the rate constant. The rate of the reaction is solely determined by the value of the rate constant, and it does not change with changes in reactant concentrations.

Explanation:

In the given question, if the reaction proceeds with a uniform rate throughout, it indicates that the rate of the reaction does not depend on the concentration of the reactants. This is a characteristic of a zero order reaction.

The rate equation for a zero order reaction is Rate = k, where k is the rate constant. It means that the reaction proceeds at a constant rate, regardless of the initial concentrations of the reactants. The rate constant determines the speed of the reaction, and it remains constant throughout the reaction.

Therefore, the correct answer is option 'D' - Zero order.

Molecularity of a reaction
  • a)
    Cannot be less than 2
  • b)
    Can be zero
  • c)
    Is always a natural number
  • d)
    Can have a fractional values
Correct answer is option 'C'. Can you explain this answer?

Nandini Nair answered
Molecularity is defined as the number of molecules, atoms, or radicals that must collide simultaneously in order for the reaction to take place. It is always a natural number and cannot be negative.

A first order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?
  • a)
    1.26 × 1015 s
  • b)
    2.52 × 1014 s
  • c)
    2.52 × 1028 s
  • d)
     infinite
Correct answer is option 'D'. Can you explain this answer?

Neha Chauhan answered
The time taken for half the reaction to complete, i.e., the time in which the concentration of a reactant is reduced to half of its original value is called half-life period of the reaction. But it is impossible to perform 100% of the reaction. Whole of the substance never reacts because in every half-life, 50% of the substance reacts. Hence, time taken for 100% completion of a reaction is infinite. 

For the first order reaction,
A → Product
Q. The concentration of A changes from 0.1 M to 0.025 M in 40 min. The rate of the reaction when the concentration of A is 0.01 M is
[AIEEE 2012]
  • a)
    1.73 x 10-6 Mmin-1
  • b)
    3.47 x 10-4 M min-1
  • c)
    3.47 x 10-5 M min-1
  • d)
    1.73 x 10-6 M min-1
Correct answer is option 'B'. Can you explain this answer?

Sanjana Bajaj answered
A first-order reaction is a type of chemical reaction where the rate of reaction is directly proportional to the concentration of one reactant. The rate equation for a first-order reaction can be written as follows:

rate = k[A]

Where:
- rate is the rate of reaction
- k is the rate constant
- [A] is the concentration of reactant A

This means that as the concentration of reactant A decreases, the rate of reaction also decreases. The half-life of a first-order reaction is constant, meaning that it takes the same amount of time for the concentration of reactant A to decrease by half, regardless of the initial concentration.

In a zero-order reaction for every 10° rise of temperature, the rate is doubled. If the temperature is increased from 10°C to 100°C, the rate of the reaction will become 
  • a)
    64 times
  • b)
    128 times
  • c)
    256 times
  • d)
    512 times
Correct answer is option 'D'. Can you explain this answer?

Ayaan Madhukar answered
For rise in temperature, n=1
Therefore rate = 2^n = 2^1 =2
When temperature is increased from 10 degree c to 100 degree c so, change in temperature = 100 -10 = 90 degree c , therefore n = 9 , therefore rate = 2^9 = 512 times...ans...

$$Hope it's help...$$

The rate equation for the reaction,
2A + B → C
is found to be, rate = k[A] [B]
Q. The correct statement in relation to this reaction is that the
  • a)
    unit of k must be s-1
  • b)
    t1/2 is constant
  • c)
    rate of formation of C is half of the rate of disappearance of A
  • d)
    value of k is independent of the initial concentration of A and 8
Correct answer is option 'C'. Can you explain this answer?

Amar Jain answered
Rate = k (A)[B]
The given reaction is first order in A and first order is B.
Thus, total order = 2
(a) Unit of k = cone 1 - n time -1 = conc-1 time-1 Thus, (a) is false.
(b)  of second-order reaction, thus (b) is false. 
Thus, (c) is correct.

Thus, value of k is dependent on the concentration of A and B. Thus, (d) is false.

Chapter doubts & questions for Chemical Kinetics - Chemistry CUET UG Mock Test Series 2026 2025 is part of NEET exam preparation. The chapters have been prepared according to the NEET exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for NEET 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.

Chapter doubts & questions of Chemical Kinetics - Chemistry CUET UG Mock Test Series 2026 in English & Hindi are available as part of NEET exam. Download more important topics, notes, lectures and mock test series for NEET Exam by signing up for free.

Top Courses NEET

Related NEET Content