Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal…

Choose the appropriate word(s) from the bracket [first, zero, second, Raoult’s law, non-ideal, addition, substitution, Henry’s law, ideal, +I, more, -I, less, dehydrohalogenation]: For a particular reaction, the value of rate constant is $0\cdot81\text{ s}^{-1}$. Hence, the reaction is of ____ order whereas in another reaction, the value of rate constant is $2\cdot5\text{ mol L}^{-1}\text{s}^{-1}$. Thus, the order of this reaction is ____.