Beryllium has an atomic number of 4. How many neutrons does the isotope beryllium-9 have?(1 point)
The isotope beryllium-9 has 5 neutrons.
To determine the number of neutrons in an isotope of an element, you can use the following formula:
Number of neutrons = Mass number - Atomic number
In this case, the isotope is beryllium-9, which means the mass number is 9. Since beryllium has an atomic number of 4, the number of neutrons can be calculated as follows:
Number of neutrons = 9 - 4 = 5
Therefore, the isotope beryllium-9 has 5 neutrons.