The nucleus!! This is made up of protons and neutrons that each weigh about 1 amu.
Electrons are not found in the nucleus and weigh almost nothing so chemistry in school doesn’t bother with them :)
Answer: 
Explanation:
Firstly we need to know that 
, then we cam make the conversion:
This is the height of Mount Everest in feet
However, we can express it using scientific notation by counting to the left the decimal spaces:
To find the number of neutrons, subtract the number of protons from the mass number. number of neutrons=40−19=21.
Answer: The particles in a solid are packed very close to each other.
