Question

In elementary reaction steps , which of the following is most likely to have the highest rate ?
A) A reaction where three reactants combine
B) A reaction with only one reactant
C) A reaction where two reactants combine
D) A reaction where two reactants undergo double displacement

Answer 1

Hint: Elementary reactions are basically reactions which take place in one step . The steps of the mechanism of complex reactions are also termed as elementary reactions .

Complete step by step answer:
In elementary reactions , all the atoms , ions or molecules of the reactants present in the balanced chemical reaction can come together simultaneously to collide with each other . Thus , such reactions take place in one step . Hence , the molecularity is simply the sum of the molecules of the different reactants as represented by the balanced chemical equation .
Now , as we know that the rate of the reaction depends on the concentration of reactants per unit time . So if there are more reactants in the reaction the rate will be higher .
Therefore , from among the given reactions the highest rate will be when three reactants combine to form the products .

So, the correct answer is Option A .

Additional Information:
There are various factors which affect the reaction rate , they are :
Nature of the reactants
Concentration of the reactants
Temperature at which the reaction takes place
Presence of a catalyst
Surface area of the reactants
Presence of light in case of photochemical reactions

Note:
Molecularity of a reaction can only be defined for an elementary reaction . It has no meaning for the complex reaction . Molecularity is the number of reacting species which are taking part in the elementary reaction step .