The speed of light meters per second

Who is better, messi or cristiano, i need this for a chemistry class. asap

How many atoms are there in 5.70 mol of mg

In a laboratory, 1.55mg of an organic compound containing carbon, hydrogen, and oxygen is burned for analysis. this combustion resulted in the formation of 1.45mg of carbon dioxide and .89 mg of water. what is the empirical formula for this compound?