The order of reaction will be if the value of rate constant is \(7.195 × 10^{-4} mol^{-3}L^3s^{-1}\)

4

The correct answer is option 4. 4.

We can find the order of the reaction from the unit of rate constant.

Unit of rate constant, \(k = conc^{1 - n}\, \ t^{-1}\); where \(n\) is the order of the reaction.

1. For First order reaction, \(n = 1\)

Unit of rate constant, \(k = (mol/L)^{1 - 1}\, \ s^{-1} = s^{-1}\)

2. For Second order reaction, \(n = 2\)

Unit of rate constant, \(k = (mol/L)^{1 - 2}\, \ s^{-1} = \, \ mol^{-1}Ls^{-1}\)

3. For Third order reaction, \(n = 3\)

Unit of rate constant, \(k = (mol/L)^{1 - 3}\, \ s^{-1} = \, \ mol^{-2}L^2s^{-1}\)

4. For Fourth order reaction, \(n = 4\)

Unit of rate constant, \(k = (mol/L)^{1 - 4}\, \ s^{-1} = \, \ mol^{-3}L^3s^{-1}\)

The unit of rate constant given in the question is thus equal to unit of fourth order reaction. So the correct answer is option 4. 4.