Chemistry Reaction Kinetics SZABMU 2023
PMDC Verified Question 16 of 80
The rate constant "k" in the rate equation is the rate of reaction when the concentration of each of the reactant is:
A
3 M
B
1 M
C
2 M
D
4 M
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 1 M
Concept:

The specific rate constant is defined mathematically by simplifying the rate law equation.

Formula:

$$ \text{Rate} = k[\text{A}]^{a}[\text{B}]^{b} $$

Solution:

  • If we set the concentration of all participating reactants to unity (exact value of 1 M or \( 1 \text{ mol dm}^{-3} \)), the equation simplifies.
  • $$ \text{Rate} = k(1)^{a}(1)^{b} = k(1) = k $$
  • Thus, \( k \) is exactly equal to the rate of reaction exclusively when all reactant concentrations are exactly 1 M.


Why other options are incorrect:

If concentrations were 2 M, 3 M, or 4 M, the rate would be a multiple of the rate constant depending on the reaction orders, not strictly equal to it.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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