Question

Identify the false statement among the following:
$(a)$ Rate of reaction is directly proportional to activation energy.
$(b)$ Order of reaction can be determined by experimental method only.
$(c)$ Rate law never coincides with the stoichiometry of the reaction.
$(d)$ Order of reaction cort different reactants may be different.

Answer 1

For such types of questions we need to understand the statement correctly, and choose the options which contain the incorrect statement. If the statement is incorrect, we should know the correct explanation of the statement.
Option: $(a)$ Rate of reaction is directly proportional to activation energy.
$(c)$ Rate law never coincides with the stoichiometry of the reaction.

Complete answer:
First statement: rate of reaction is directly proportional to activation energy.
Activation energy of a chemical reaction is closely related to its rate. The higher the activation energy, the slower the chemical reaction will be. This is because molecules can only complete the reaction once they have reached the top of the activation energy barrier. The higher the barrier is, the fewer molecules that will have enough energy to make it over, thus, activation energy is inversely proportional to rate of reaction. So this statement is false.
Second statement: order of reaction can be determined by experimental method only.
Order of reaction is defined as the sum of power of concentration of reactants in the rate law expression, order of reaction is experimental value because if we know the rate law expression determined experimentally then we can determine order of reaction using rate law. It is an experimentally derived parameter. So, this statement is true.
Third statement: Rate law never coincides with the stoichiometry of reaction.
Stoichiometry of a reaction tells about the order of the elementary reactions. For an elementary reaction, the order of reaction with respect to a reactant is equal to the stoichiometry coefficient of the reactant. So, this statement is false.
Fourth statement: order of reaction cort different reactants may be different.
Order of reaction can be an integer value or a fractional value depending on the reactants. Order of reaction can be zero, order of reaction can be negative integer, order of reaction can be positive integer, and order of reaction can be fractional number. So, this statement is true.

Option (a) and (c) are the false statements.

Note:
Option $(a)$ is wrong as rate of reaction is inversely proportional to the activation energy required for that reaction. Also option $(c)$ is wrong because the rate does coincide with the stoichiometry for elementary reactions, which take place in one step.