One day, Jack and John was walking on the street. They felt thirsty, but there wasno restaurant or supermarket on that street. Suddenly they found a chemical store.They ran to the store. Jack asked the salesman,"I'm thirsty. Could you please giveme some H2O?" The salesman gave him a bottle. Jack drank it then felt better. Then John asked the salesman, "I want some H2O, too." The Salesman gave him a bottle, too. He drank it but then he died. Do you know why?