Polished steel surface is the smoothest among the given surfaces because it has the least irregular surface followed by cardboard and sandpaper respectively. If we try to slide a block with same speed on all these surfaces, the block will move farthest on the polished steel surface because it offers the least friction.

Friction that exists between two surfaces in contact when there is no relative motion between them is known as static friction. It is a self-adjusting force which has a maximum limit. When the applied force overcomes this maximum value of static friction, the object starts moving. After this, kinetic or sliding friction comes into play.

Wheels are added to trolleys to reduce friction. As rolling friction is lesser than sliding friction, adding wheels to trolleys reduces opposition to motion.

By polishing or using ball bearings and lubricants, we can decrease friction between two solid surfaces. However, to decrease air drag, we can use streamlined objects which can easily move through air without much resistance.

Friction depends on the nature of surfaces in contact and the force with which the surfaces are pressed against each other. It doesn't depend on the area of contact. Thus, frictional force will not change even if the given object is dragged along the top surface instead of the bottom.

Frictional force is the opposing force which resists the relative motion between two solid surfaces, two fluid layers or a solid surface and a fluid layer. It can only act when there is physical contact between two surfaces. In all the situations except that of the Moon revolving around Earth, some friction is experienced as there is relative motion between two objects in contact. However, the Moon orbits Earth in space where there is a vacuum. Hence, no frictional force is involved in this case.

Any object moving through a fluid (liquid or gas) experiences a frictional or drag force which opposes its motion. Hence, motion of the aeroplane will be retarded by air. Thus, the given statement is false.