The Arrhenius equation shows that the rate constant k increases with temperature because of:

• A. The Arrhenius pre-exponential factor A decreases with T
• B. The exponential term exp(-Ea/RT) decreases with T
• C. The activation energy Ea decreases with T
• D. The exponential term exp(-Ea/RT) increases with T

Answer: (D)

As temperature rises, more molecules have enough energy to overcome the activation barrier. In the Arrhenius form, k = A exp(-Ea/RT), the only part that increases when T goes up is the exponential term exp(-Ea/RT). Increasing T makes Ea/RT smaller, so the negative exponent becomes less negative, and the exponential factor grows. That rise in exp(-Ea/RT) drives k upward, which is why the rate constant increases with temperature.

The activation energy Ea and the pre-exponential factor A are treated as constants in this relation, so they don’t explain the temperature rise on their own. If A were to decrease with temperature, it could offset the increase, but the standard explanation relies on the exponential term growing with T.