Which term is the symbol for the rate constant? a. [a] b. k c. r d. x + y e. none of the above

            Option-B (k) is the correct answer.

Explanation:
                   As we know the rate of reaction is given as;

                                                Rate  =  k [A]ˣ
Where;
            Rate  =  Rate of Reaction

            k  =  rate constant
 
            [ ]  =  concentration of A

            x  =  order of reaction

So, from this equation we found that rate of reaction depends upon concentration and rate constant (k).
Now,
The rate constant is as follow,,

                                            k  =  Ae^(Ea/RT) 

This equation is known as Arrhenius Equation, according to this equation rate constant depends upon Temperature and Activation energy. Greater the temperature greater is the rate constant and hence greater is the rate of reaction. Or smaller the activation energy greater is the rate constant and vice versa.