Which of the following statements is incorrect with respect to physisorption?

\(\Delta H <0\)

The correct answer is option 4. \(\Delta H < 0\).

Physisorption is a type of adsorption where molecules adhere to a surface due to weak van der Waals forces, such as dispersion forces, dipole-dipole interactions, and hydrogen bonding. Here's why the statement "ΔH < 0" is correct in the context of physisorption:

Definition of ΔH: ΔH represents the change in enthalpy during a process. Enthalpy is a measure of the total energy of a system, including both its internal energy and the energy associated with pressure and volume.

Release of Energy: In physisorption, when molecules are adsorbed onto a surface, they release energy. This is because the weak intermolecular forces between the adsorbate molecules and the surface are more favorable energetically than the interactions between the adsorbate molecules themselves in the gas or liquid phase.

Negative ΔH: Whenever energy is released from a system, the change in enthalpy (ΔH) is negative. This indicates that the overall energy of the system decreases during the process.

In summary, the statement "ΔH < 0" is correct in the context of physisorption because energy is released when molecules are adsorbed onto a surface due to weak intermolecular forces. Therefore, it's an exothermic process, and the change in enthalpy is negative.