Question

suppose you needed to build a raft to cross a fast-moving river. Describe the physical and chemical properties of the raft that would be important to ensure your safety.

Answer 1

1.Density of the material building the raft must be lower than the water. 
2. Material must not react with water. 
3.Material must have high strength. 
4.Raft must be wide in-order to avoid drawing in the river.