Question

question 10
how many neutrons does $^{40}$ca contain?
periodictable.pdf
○ a. 20
○ b. 40
○ c. 18
○ d. 22

Explanation:

Step1: Identify mass and atomic number

For $^{40}\text{Ca}$, mass number $A=40$, atomic number (proton count) $Z=20$ (from periodic table).

Step2: Calculate neutron count

Neutrons = Mass number - Protons, so $N = A - Z$
$N = 40 - 20$

Answer:

a. 20