Answer: I believe it’s D. Twice
Hope this’ll help! ^^
Answer:
pipette is used to transfer a sample to a microscope slide.
The mass number is the sum of the number of protons and number of neutrons the atom has.
So, we can write the equation as:
x + 20 = 40
x = 20 neutrons.
If one organ doesnt work ex. kidney it can work without the other one. if the liver how ever fails, it doesnt have another one and would need to have a transplant in order to stay alive.