When asked to name all the forces on a marker sitting in equilibrium on a desk, a student responds: "Since the marker on the desk is at rest, there are no forces

acting on it." Why is this wrong? How would you restate it?

The forces acting on the pen which is still on the table can have two forces acting on them. The forces are gravitational force and the equal and opposite force to the gravitational forces.

The equal and opposite forces that is applied on the pen keeps the pen still on the table.

So, the statement that no force is applied on the pen which is kept still on the table is wrong as two forces are applied on the pen.

As both the forces are equal and opposite so it is cancelled and is still.