When methane, CH4, is combusted, it produces carbon dioxide, CO2, according to the unbalanced equation: CH4 + O2 → CO2 + H2O. Write the balanced equation for this reaction, and explain how it is possible for 10 grams of methane fuel to burn and emit 27 grams of carbon dioxide. Discuss whether or not this reaction obeys the law of conservation of mass. (5 points)

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.