Collision theory of reaction rates — NEET & JEE Questions

Question 1 · difficulty L1 · recall

According to collision theory, a reaction occurs when reacting particles undergo

• A. effective collisions
• B. any collision whatsoever
• C. no collisions
• D. only elastic collisions

Question 2 · difficulty L2 · understanding

For a collision to be effective, colliding molecules generally need

• A. sufficient energy and proper orientation
• B. only high mass
• C. only identical speed
• D. zero kinetic energy

Question 3 · difficulty L2 · understanding

Activation energy is the minimum energy barrier that

• A. reacting particles must overcome for reaction to occur
• B. products must lose after formation
• C. a catalyst creates
• D. is always zero

Question 4 · difficulty L2 · understanding

A catalyst increases reaction rate mainly by

• A. providing an alternative pathway with lower activation energy
• B. increasing reactant enthalpy permanently
• C. increasing equilibrium constant in all cases
• D. making every collision perfectly oriented

Question 5 · difficulty L3 · application

If temperature increases, reaction rate often increases because

• A. a larger fraction of molecules have energy above the activation threshold
• B. activation energy always becomes zero
• C. all molecules stop colliding
• D. molecular orientation becomes irrelevant

Question 6 · difficulty L3 · application

Increasing concentration of reactants in a gas-phase reaction generally increases rate because

• A. collision frequency increases
• B. activation energy necessarily doubles
• C. molecules become larger
• D. products become catalysts

Question 7 · difficulty L3 · application

A reaction has frequent collisions but remains slow. Which explanation is most consistent with collision theory?

• A. Few collisions have sufficient energy or correct orientation
• B. No particles are moving
• C. Every collision is effective
• D. The activation energy is negative

Question 8 · difficulty L3 · application

Adding a catalyst to a reaction at the same temperature increases the number of effective collisions mainly because

• A. the energy threshold for reaction is lowered
• B. molecules become hotter
• C. the collision frequency must become infinite
• D. the catalyst changes reactants into products without collisions

Question 9 · difficulty L4 · application

Two reactions have the same collision frequency and orientation factor, but reaction P has a lower activation energy than Q. At the same temperature, which is generally faster?

• A. P
• B. Q
• C. They must be identical
• D. No prediction is possible from activation energy

Question 10 · difficulty L4 · application

A reaction between complex molecules has enough collision energy but a very small orientation factor. What does collision theory predict?

• A. Many collisions still fail to react because geometry is unsuitable
• B. Every collision reacts
• C. Activation energy becomes irrelevant and rate is maximal
• D. The reaction must be diffusionless