fossils may scientist to determine how previous species and or humans lived in the past. it's beneficial to us because if we can determine how they live we can see how they died and what era they came from not only that it can us in the future to prevent diseases that may have been a cause back then. we can also link what species of fossils are link to certain animals or plants also.
the correct answer would be 57.
atomic number is defined as the total number of protons in an atom. thus, the number of protons in element x would be 29.
in addition, the mass number is defined as the sum of neutrons and protons present in an atom.
therefore, the sum of the number of neutrons and protons in an element x would be 86.
thus, the number of neutrons = mass number- the number of protons
hence, the number of neutrons would be equal to 57.