The diagram below shows four layers of Earth. Helium atom. There are two particles with negative charge in the outer-most region of the atom, two particles with positive charge (labeled 'A.' The layer around the central region is labeled 'B.' The outermost layer is labeled 'D.' The layer inside Earth which is just after layer D is labeled 'C.' Which of these layers is composed of materials with a plastic nature? (3 points) Group of answer choices Layer D Layer B Layer C Layer A

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.

i do not get it   at all

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.