Question

the number of neutrons and protons in calcium - 40 are ____ and ____ respectively.
a 18, 18
b 18, 20
c 20, 18
d 20, 20

Explanation:

Step1: Determine the number of protons

The atomic number of calcium (\(Ca\)) is \(20\). The number of protons in an atom is equal to its atomic number. So, the number of protons \(= 20\).

Step2: Calculate the number of neutrons

The mass number of calcium - 40 is \(40\). The formula to calculate the number of neutrons is \(n=\text{Mass number}-\text{Atomic number}\).
Substituting the values, we get \(n = 40 - 20=20\).

Answer:

D. \(20,20\)