Concept:Map scale expresses the relationship between a distance measured on the map and the actual distance on the ground.Explanation:The map of Nonso District has a representative fraction scale of 1:50,000.This means that 1cm on the map represents 50,000cm on the ground.Convert 50,000cm into kilometers: since 1km=100,000cm, we get 100,00050,000=0.5km.Therefore, 1cm on the map equals 21km or half a kilometer on the ground.Answer:One centimeter on the map represents 21 kilometer on the ground.