Beryllium has an atomic number of 4. How many neutrons does the isotope beryllium-9 have? (1 point)

Question

5

9

4

13

Answer 1

To find the number of neutrons in an isotope, you can use the following formula:

\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]

For beryllium-9:

• The mass number is 9.
• The atomic number is 4 (which corresponds to the number of protons).

Now, substitute the values:

\[ \text{Number of Neutrons} = 9 - 4 = 5 \]

Therefore, the isotope beryllium-9 has 5 neutrons.