Which of the following is not affected by an increase in temperature?

a. collision energy.
b. collision frequency.
c. collision orientation.

Option c. The orientation required for a successful (fruitful) collision won't change as long as the reaction mechanism stays the same.

Explanation:

Average collision energy depends on the temperature. For each collision, the energy supplied depends on the kinetic energy of the two particles that ran into each other. Consider a reaction where both reactants are gases. By the kinetic theory of gases, the average kinetic energy of the collision will be proportional to the absolute temperature.

.

Increasing the temperature will increase the average kinetic energy supplied in each collision. A similar relationship exist for solids and liquids. Generally, increasing the temperature makes it more likely for the collisions to be fruitful.

Average collision frequency also depends on the temperature. As the temperature increases, the particles move at a faster rate. They are more likely to run into each other. As a result, the frequency of collision will increase.

Many of the collisions are sufficiently energetic. However, only the collisions that are in the right orientation will produce the product. The exact orientation required for a reaction depends on the mechanism of that reaction. As long as the temperature change does not influence the way the reaction takes place, the orientation required should stay the same.