The reaction with hydrogen with oxygen produces water: 2 H2 + O2 ---> 2H20. How many moles of O2 are required to react with 2.0 mol of H2? *

the answer for sodium is 0.186

the answer for rubidium is 0.251

answer;

18.5 seconds

explanation;

velocity is distance covered per unit time; it is given by displacement divided by time.

thus; time = displacement/velocity

total time = total displacement/velocity

total distance = 5000 meters south

total time = 5000/4.5

                  = 1111.11 seconds

but; 1 minute = 60 sec

thus; 1111.11 /60

                = 18.51 seconds

thus; the time taken is 18.5 seconds