What will be the initial rate of a reaction if its constant is 10^–3 min^–1 and the concentration of reactant is 0.2 mol dm³?

0.0002 mol dm^–3 min^–1

The correct answer is option 3. 0.0002 mol dm^–3 min^–1.

To determine the initial rate of a reaction, we can use the rate equation:\(\text{Rate} = k[A] \)

where \(\text{Rate}\) is the rate of the reaction, \(k\) is the rate constant, and \([A]\) is the concentration of the reactant.

Given that the rate constant (\(k\)) is \(10^{-3} \, \text{min}^{-1}\) and the concentration of the reactant (\([A]\)) is \(0.2 \, \text{mol dm}^{-3}\), we can substitute these values into the rate equation to find the initial rate (\(\text{Rate}_0\)):

\(\text{Rate}_0 = k \times [A] \)

\(\text{Rate}_0 = (10^{-3} \, \text{min}^{-1}) \times (0.2 \, \text{mol dm}^{-3}) \)

\(\text{Rate}_0 = 2 \times 10^{-4} \, \text{mol dm}^{-3} \text{ min}^{-1} \)

Therefore, the correct answer is \((3) \, 0.0002 \, \text{mol dm}^{-3} \, \text{min}^{-1}\).