Consider the given graph showing variation of reactant concentration with time.
Three different reactions were started with identical initial concentration of reactants. Which of the following statement is correct?
- A
The order of all the three reactions is same.
- B
The rate constant of reaction 3 is larger than the rate constant of reaction 2 if the order of reaction is same for both.
- C
The SI unit of rate constant of reaction 1 is s.
- D
Thermal decomposition of HI on gold surface is an example of reaction 2.
Curve 1 is a straight line from [R] — characteristic of zero-order kinetics: .
Curves 2 and 3 are exponential decays (first-order or higher). Among them, curve 3 decays faster, so its rate constant is larger if both have the same order.
Now check each option:
(1) Wrong — curve 1 is zero-order while curves 2 and 3 are not, so orders differ.
(2) Correct — for the same order, the faster-decaying curve (3) has the larger rate constant.
(3) Wrong — SI unit of rate constant for a zero-order reaction is mol L s (concentration/time), not s.
(4) Wrong — thermal decomposition of HI on gold surface is a classic example of a zero-order reaction (curve 1), not curve 2.
Practice more Chemistry
Concept-wise practice with instant solutions on Fundamenthol.
Start practicing →