Four identical weights are each 5 kilograms. What is the range of these four weights?

Explication

The largest and smallest weights are both 5 kilograms, so the range is 5 - 5 = 0 kilograms. Answering 5 kilograms repeats the value every weight shares, yet a range of 0 is exactly the message here, because identical values leave no distance at all between the extremes.