A hydrocarbon is a compound made of carbon and hydrogen atoms. An unknown hydrocarbon is found to contain 85.7% carbon, 14.3% hydrogen and an atomic mass of 84.0 g/mol. What is its molecular formula?

Atrain travels 74 kilometers in 3 hours, and then 81 kilometers in 5 hours. what is its average speed?

Chlorophyll a had the molecular formula c55h72mgn4o5 how many atoms are in this molecule

4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temperature drops from 22.0 c to 16.9 c. assume that the specific heat of the solution is the same as that of pure water. calculate delta(h) (in kj/mol nh4no3) for the solution proces.