Collision theory postulates are:
A. Reactant molecules collide with each other.
B. The collisions must be of sufficient kinetic energy.
C. The collision in molecules with proper orientation.
D. Rate of reaction does not depend on temperature.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A, B and C only
Collision theory treats reactant molecules as hard spheres; the rate depends on the collision frequency and on the fraction of collisions that are effective.
A. Reactant molecules collide with each other — Correct. A reaction is assumed to occur only when the molecules collide.
B. The collisions must be of sufficient kinetic energy — Correct. Colliding molecules need at least the threshold energy to break the old bonds.
C. The collision in molecules with proper orientation — Correct. Even energetic collisions give products only with proper orientation (the steric factor P).
D. Rate of reaction does not depend on temperature — Incorrect. A rise in temperature increases the fraction of molecules with the threshold energy, so the rate rises (k = PZABe−Ea/RT).
NCERT (2026-27 edition):
Collision Theory of Chemical Reactions – “Though Arrhenius equation is applicable under a wide range of circumstances, collision theory, which was developed by Max Trautz and William Lewis in 1916 -18, provides a greater insight into the energetic and mechanistic aspects of reactions. It is based on kinetic theory of gases. According to this theory, the reactant molecules are assumed to be hard spheres and reaction is postulated to occur when molecules collide with each other. … The collisions in which molecules collide with sufficient kinetic energy (called threshold energy) and proper orientation, so as to facilitate breaking of bonds between reacting species and formation of new bonds to form products are called as effective collisions.”