Which of the following statements is incorrect, if any? the normal force always points upward (positive y-direction). the normal force is a contact force. the normal force arises from compression of molecular bonds. all statements are correct.

The following statement is incorrect: The normal force always points upward (positive y-direction).

Explanation:

The normal force, as his names points out, is always normal to the surface on which the object that is being acted on by this force is placed.

This means that it will always be at straight angles with the surface, regardless of the orientation of the surface.

For instance, in an inclined plane, is directly related with the angle that the plane has with the horizontal, and can be even horizontal if the surface is a vertical wall.

The normal force is one of the components of the contact force (the other one is the fricition force, always parallel to the contact surface), and adopts any needed value to satisfy the Newton's 2nd Law.