Question

which applies to the collision theory?
particles need to collide in order to react.
particles may obtain successful collisions in any molecular orientation.
temperature increase causes kinetic energy of particles to decrease.
reactions do not have to begin with collision of molecules or particles.

Explanation:

• For the first option: Collision theory states that for a reaction to occur, reactant particles must collide. This is a key principle of collision theory.
• For the second option: Successful collisions (effective collisions) require a specific orientation of molecules, not any orientation. So this is incorrect.
• For the third option: An increase in temperature increases the kinetic energy of particles (as kinetic energy is related to temperature by \( KE=\frac{3}{2}kT \) for ideal gases, where \( k \) is Boltzmann constant and \( T \) is temperature), so this is incorrect.
• For the fourth option: Collision theory emphasizes that reactions start with the collision of molecules/particles, so this is incorrect.

Answer:

A. Particles need to collide in order to react.