How many elements have to be present for a compound to form?

Problem page gaseous ethane reacts with gaseous oxygen gas to produce gaseous carbon dioxide and gaseous water . if of water is produced from the reaction of of ethane and of oxygen gas, calculate the percent yield of water. be sure your answer has the correct number of significant digits in it.

Which produce would best increase the amount of heat energy that is actually gained by calorimeter b

What overall charge must all compounds have