According to the law of conservation of matter, which statement about chemical reactions is true?
a. every atom destroyed in a chemical reaction must be replaced.
b. atoms are created by some reactions and destroyed by others.
c. energy is created as atoms are destroyed in chemical reactions.
d. atoms cannot be created or destroyed by chemical reactions.

answer: h+ its less than oh

explanation:

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.

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa