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ISC Class 12 Chemical Kinetics — practice questions — page 3

Explore 66 free Chemical Kinetics questions in ISC Class 12 Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Chemical Kinetics questions and exercises with answers

Showing questions 61–66 of 66.

Order the steps: find the order of a reactionRead the answer and worked solution →Three of these are wrong. Find the one that holds.Read the answer and worked solution →NEET · Chemistry · Rate Law — Gap FillRead the answer and worked solution →For a first-order reaction, the half-life period $t_{1/2}$ is related to the rate constant $k$ as:Read the answer and worked solution →Complete the definition of orderRead the answer and worked solution →Order or molecularity?Read the answer and worked solution →

Worked practice questions

Order the steps: find the order of a reaction

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Steps
  1. Measure how the rate changes as each concentration is varied
  2. Fit those measurements to a rate law
  3. Read the power of each concentration as its order
  4. Add the powers to get the overall order
  5. The proportionality factor left over is the rate constant
Everything begins with measurement, because the rate law cannot be predicted. Source: syllabus Chemistry Part I, Ch 3 Chemical Kinetics.

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Three of these are wrong. Find the one that holds.

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Questions
  1. Question
    Three of these statements about molecularity are false.
    Choices
    1. Item
      Defined only for elementary reactions
      Correct
      Yes
    2. Explanation
      Molecularity runs from 1 to 3.
      Item
      It can be zero
    3. Explanation
      Only ORDER can be fractional.
      Item
      It can be a fraction
    4. Explanation
      It comes from the proposed mechanism, not measurement.
      Item
      It is found by experiment
  2. Question
    Three of these statements about activation energy are false.
    Choices
    1. Item
      Activated complex minus reactant energy
      Correct
      Yes
    2. Explanation
      A catalyst LOWERS the activation energy.
      Item
      A catalyst raises it
    3. Explanation
      It is a difference, not the product energy.
      Item
      It is the energy of the products
    4. Explanation
      A higher barrier slows the reaction.
      Item
      Raising it speeds the reaction up
Each trap is a real confusion between the measured and the mechanistic. Source: syllabus Chemistry Part I, Ch 3 Chemical Kinetics.

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NEET · Chemistry · Rate Law — Gap Fill

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Missing parts
  1. Answer
    m + n
    Choices
    1. m + n
    2. m × n
    3. m − n
    4. max(m, n)
  2. Answer
    L mol⁻¹ s⁻¹
    Choices
    1. s⁻¹
    2. L mol⁻¹ s⁻¹
    3. L² mol⁻² s⁻¹
    4. mol L⁻¹ s⁻¹
Complete the statement
For a reaction Rate = k[A]^m [B]^n, the order of reaction is {0} and the units of k for a second-order reaction (overall order 2) are {1}.
Instructions
Fill the order expression and the units of the rate constant.

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