The density of copper is 8.9 g/mL. What is the volume of 20.5 g copper?

density = 8.9 g/ml

m = 20.5 g

V = ... ?

density = m/V

V = m / density

= 20.5 / 8.9

= 2.30337 ml

the major pests we deal with are insects, weeds and fungal diseases. a pesticide is a product, whether organic or chemical, used to kill the target pest. there are other techniques gardeners should use that can prevent the severe infestations that make the use of pesticides necessary

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.