Answer:
20
Explanation:
number of protons+ number of neutrons= mass of atom
19+n=39
n=39-19=20
number of neutrons=20
It can help to go over the main ideas or important moments of the story and then see what those are portraying, whether there is a lesson or not. you can also look at the ideas of the characters and what they are thinking to determine the theme.
The correct answer would be B wear sunscreen because in the desert it is really hot and doesn't rain. So sunscreen would protect you from the sun.
A *life support system* is defined as the interrelationship between living beings and environment.