Choose the incorrect statement.

The rate of reaction decreases with a rise in temperature.

The correct answer is option 4. The rate of reaction decreases with a rise in temperature.

The statement "The rate of reaction decreases with a rise in temperature" is incorrect. It's a fundamental principle in chemistry that the rate of many chemical reactions increases with an increase in temperature. This phenomenon is described by the Arrhenius equation, which relates the rate constant of a reaction (k) to the temperature (T) and the activation energy (Ea) of the reaction:

\[ k = A \times e^{\frac{-E_a}{RT}} \]

Where:
- \( k \) is the rate constant,
- \( A \) is the pre-exponential factor (also known as the frequency factor), which represents the frequency of collisions between reactant molecules,
- \( e \) is the base of the natural logarithm,
- \( E_a \) is the activation energy,
- \( R \) is the gas constant, and
- \( T \) is the temperature in Kelvin.

From this equation, it's evident that as temperature (\( T \)) increases, the exponential term becomes larger, leading to a higher rate constant (\( k \)). This means that the rate of reaction increases with temperature for reactions where the activation energy is positive.

This increase in reaction rate with temperature can be explained by the kinetic molecular theory. At higher temperatures, molecules possess more kinetic energy, and they move faster. As a result, they collide more frequently and with greater energy, leading to a higher probability of successful collisions and, consequently, a higher reaction rate.

There are exceptions to this general rule, particularly for reactions where the increase in temperature leads to significant changes in the mechanism of the reaction or where temperature effects on equilibrium become dominant. However, these exceptions are not common and do not negate the overall trend of increased reaction rates with increasing temperature in most cases.