Question

question 5. how many neutrons does a beryllium atom with four protons and a mass number of nine have? number of neutrons =

Explanation:

Step1: Recall the formula

The mass number (A) is the sum of the number of protons (p) and neutrons (n), i.e., $A=p + n$.

Step2: Rearrange the formula

We can solve for the number of neutrons $n$ as $n=A - p$.

Step3: Substitute the values

Given that $A = 9$ and $p = 4$, then $n=9 - 4$.

Step4: Calculate the result

$n = 5$.

Answer:

5