how many neutrons are in a calcium (ca) atom? atomic mass: 40.078 atomic number: 20 9 33 20

Explanation:

Step1: Recall neutron - proton relation

The number of neutrons ($n$) in an atom is calculated by subtracting the atomic number ($Z$) from the mass number ($A$). For simplicity, we usually round the atomic mass to the nearest whole number to get the mass number. Rounding 40.078 gives 40.

Step2: Calculate number of neutrons

We know that $A = 40$ and $Z=20$. Using the formula $n=A - Z$, we substitute the values: $n = 40-20$. $n = 20$

Answer:

20