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

Assertion: The enthalpy of reaction remains constant in the presence of a catalyst. Reason: A catalyst participating in the reaction, forms different activated complex and lowers down the activatio - Chemistry

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प्रश्न

Assertion: The enthalpy of reaction remains constant in the presence of a catalyst.

Reason: A catalyst participating in the reaction, forms different activated complex and lowers down the activation energy but the difference in energy of reactant and product remains the same.

विकल्प

  • Both assertion and reason are correct and the reason is correct explanation of assertion.

  • Both assertion and reason are correct but reason does not explain assertion.

  • Assertion is correct but reason is incorrect.

  • Both assertion and reason are incorrect.

  • Assertion is incorrect but reason is correct.

MCQ
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उत्तर

Both assertion and reason are correct and the reason is correct explanation of assertion.

Explanation:

AH = Activation Energy of forward reaction – Activation Energy of reverse reaction.

Catalyst does not alter heat of reaction because it affects activation energy of forward and reverse reactions equally.

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अध्याय 4: Chemical Kinetics - Exercises [पृष्ठ ५९]

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एनसीईआरटी एक्झांप्लर Chemistry [English] Class 12
अध्याय 4 Chemical Kinetics
Exercises | Q V. 59. | पृष्ठ ५९

संबंधित प्रश्न

For the first order thermal decomposition reaction, the following data were obtained:

Time / sec               Totalpressure / atm

0                              0.30

300                          0.50

Calculate the rate constant

(Given: log 2 = 0.301, log3 = 0.4771, log 4 = 0.6021)


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

Rate = k [A] [B]2

What is the overall order of reaction if A is present in large excess?


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


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?


Write resonating structures of ozone.


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


The value of rate constant of a pseudo first order reaction ______.


In any unimolecular reaction:

(i) only one reacting species is involved in the rate determining step.

(ii) the order and the molecularity of slowest step are equal to one.

(iii) the molecularity of the reaction is one and order is zero.

(iv) both molecularity and order of the reaction are one.


Why is the probability of reaction with molecularity higher than three very rare?


Why can’t molecularity of any reaction be equal to zero?


In the presence of a catalyst, the heat evolved or absorbed during the reaction.


If the 0.05 molar solution of m+ is replaced by a 0.0025 molar m+ solution, then the magnitude of the cell potential would be


For reaction 2A + B → BC + D which of the following does not Express the reaction rates


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

L mol–1 s–1


The conversion of molecules A to B follow second order kinetics. If concentration of A is increased to three times, how will it affect the rate of formation of B?


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.
    [log 4 = 0.6021, log 3 = 0.4771, log 2 = 0.3010, log 10 = 1]    [2]

A drop of solution (volume 0.05 ml) contains 3.0 × 10-6 mole of H+. If the rate constant of disappearance of H+ is 1.0 × 107 mole l-1s-1. It would take for H+ in drop to disappear in ______ × 10-9s.


Assertion (A): Order of reaction is applicable to elementary as well as complex reactions.

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


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


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