How much heat is evolved when 2 moles of methane (ch4) is burned according to this equation? ch4(g) + 2o2(g) co2(g) + 2h2o(l) hcomb = -890 kj/mol. a. -1780 kj. b. 445 kj. c. 1780 kj. d. 27,400 kj

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.