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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

A reaction is first order in A and second order in B. How is the rate affected when the concentrations of both A and B are doubled?

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प्रश्न

A reaction is first order in A and second order in B. How is the rate affected when the concentrations of both A and B are doubled?

A reaction is of first order with respect to reactant [A] and second order with regard to reactant [B]. What is the effect on rate of reaction when concentrations of both [A] and [B] are doubled?

संख्यात्मक
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उत्तर

When the concentrations of both A and B are doubled,

Rate = k(2a) (2b)2

= k(2a) (4b2)

= 8 kab2

∴ The reaction rate will increase by a factor of 8.

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2025-2026 (March) Official Board Paper

संबंधित प्रश्न

For a reaction: 

Rate = k

(i) Write the order and molecularity of this reaction.

(ii) Write the unit of k.


For a reaction A + B ⟶ P, the rate is given by

Rate = k [A] [B]2

How is the rate of reaction affected if the concentration of B is doubled?


Mention the factors that affect the rate of a chemical reaction.


A reaction is second order with respect to a reactant. How is the rate of reaction affected if the concentration of the reactant is doubled?


A reaction is first order in A and second order in B. Write the differential rate equation.


For a reaction R ---> P, half-life (t1/2) is observed to be independent of the initial concentration of reactants. What is the order of reaction?


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\[\ce{C3H8_{(g)} + 5O2_{(g)} -> 3CO2_{(g)} + 4H2O_{(g)}}\]


Molecularity of a reaction _____________.


Which of the following statements is not correct about order of a reaction.


For which type of reactions, order and molecularity have the same value?


Why can we not determine the order of a reaction by taking into consideration the balanced chemical equation?


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Identify the order of reaction from the following unit for its rate constant:

L mol–1 s–1


Read the following passage and answer the questions that follow:

The rate of reaction is concerned with decrease in the concentration of reactants or increase in the concentration of products per unit of time. It can be expressed as instantaneous rate at a particular instant of time and average rate over a large interval of time. A number of factors such as temperature, concentration of reactants, catalyst affect the rate of reaction. Mathematical representation of rate of a reaction is given by rate law:

Rate = k[A]x [B]y

x and y indicate how sensitive the rate is to change in concentration of A and B. Sum of x + y gives the overall order of a reaction.
When a sequence of elementary reactions gives us the products, the reaction is called complex reaction. Molecularity and order of an elementary reaction are same. Zero-order reactions are relatively uncommon but they occur under special conditions. All natural and artificial radioactive decay of unstable nuclei takes place by first-order kinetics.

  1. What is the effect of temperature on the rate constant of a reason?    [1]
  2. For a reaction \[\ce{A + B → Product}\], the rate law is given by, Rate = k[A]2 [B]1/2. What is the order of the reaction?    [1]
  3. How order and molecularity are different for complex reactions?    [1]
  4. A first-order reaction has a rate constant 2 × 10–3 s–1. How long will 6 g of this reactant take to reduce to 2 g?    [2]
    OR
    The half-life for radioactive decay of 14C is 6930 years. An archaeological artifact containing wood had only 75% of the 14C found in a living tree. Find the age of the sample.
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Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.

Reason (R): For a complex reaction, molecularity has no meaning.


Higher yield of NO in \[\ce{N2(g) + O2 <=> 2NO(g)}\] can be obtained at:

[ΔH of the reaction = +180.7 kJ mol−1]

  1. higher temperature
  2. lower temperature
  3. higher concentration of N2
  4. higher concentration of O2

Choose the correct answer from the options given below:


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