Read the Passage carefully and answer the Questions.
Kinetic studies not only help us to determine the rate of a chemical reaction but also describe the conditions by which the reaction rates can be altered. The factors such as concentration, temperature, pressure and catalyst affect the rate of a reaction. The speed of a reaction or the rate of a reaction can be defined as the change in concentration of a reactant or product in unit time.
Rate = $k [A]^x [B]^y$
Here k is the rate constant
$x + y$ gives the overall order of a reaction, whereas x and y represent the order with respect to the reactants A and B, respectively.
The unit of rate constant for first order reaction is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → $s^{-1}$
For a first-order reaction, the rate law is:
$\text{Rate} = k[A]$
Rate has units of concentration per time $(\text{mol L}^{-1}\text{s}^{-1})$.
So, the unit of $k$ is:
$k = \frac{\text{Rate}}{[A]} = \frac{\text{mol L}^{-1}\text{s}^{-1}}{\text{mol L}^{-1}} = \text{s}^{-1}$