Which of the following is true of oxygen? A. Oxygen is an element because its most basic unit is a single type of atom.
B. Oxygen is a compound because its most basic unit is a single type of atom.
C. Oxygen is a mixture because its most basic unit contains more than one particle.
D. Oxygen is a compound because its most basic unit contains more than one type of particle.

- lead + phosphoric acid = hydrogen + lead(ii) phosphate

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.

answerspecific gravity;