The correct expression of the rate of the reaction according to the collision theory is

$PZ_{AB} e^{-Ea/RT}$

The correct answer is Option (2) → $PZ_{AB} e^{-Ea/RT}$

Collision theory states that for a reaction to occur, molecules must collide with:

• Sufficient energy (≥ activation energy)
• Proper orientation

So rate depends on number of collisions, orientation factor, and energy factor.

Option 2: $PZ_{AB} e^{-E_a/RT}$

Complete expression of collision theory rate constant:

• $Z_{AB}$ = collision frequency
• $P$ = steric factor (proper orientation)
• $e^{-E_a/RT}$ = fraction of energetic molecules

This matches Arrhenius form $k = Ae^{-E_a/RT}$, where $A = PZ$.