State any one condition under which a bimolecular reaction may be kinetically of first order

Using cyanide and bromopropane as an example:

Reaction: C3H7Br + CN- -------------C3H7CN + Br-

The reaction involves two reactants, so it is a2ndorder reaction:

Using cyanide and bromopropane as an example:
In this case, the concentration of cyanide (CN-)equals 100M, which is significantly higher than the concentration of bromopropane. Because the concentration of cyanide issignificantly higher than the concentration of bromopropane, we can assume cyanide's concentration will stay constant in the reaction.

AS THE concentration is significantly large so it is first order reaction