There are different orders for different reactions. It can be zero order, first order, second order, pseudo-first-order, etc
The exponent on each concentration term is the order of the reaction in that particular reactant
Since it is experimentally determined, it can be integers, fractions.
2N2O5→4NO2+O2
Rate (r)=k[N2O5]
It is a first-order reaction that is not equal to the stoichiometry of the reactants in a balanced chemical equation.
Now on checking the options, the order of a reaction can be a fractional number.
The order of a reaction is experimentally determined.
order is the sum of the powers to which the concentration of reactants is raised in a rate law expression.
Therefore, options A, B, and D have correct statements.
And option C is an incorrect statement.