Question

calcium - 44 contains __ protons, neutrons, & __ electrons.

a. 20, 24, 20
b. 24, 20, 24
c. 20, 44, 20
d. 20, 44, 24

Explanation:

Step1: Recall atomic number of calcium

Calcium has atomic number 20. Atomic number = number of protons = number of electrons in a neutral atom. So, number of protons = 20 and number of electrons = 20.

Step2: Calculate number of neutrons

Mass - number of an isotope is sum of protons and neutrons. Given calcium - 44 has mass - number 44. Number of neutrons=Mass number - Number of protons. So, number of neutrons = 44 - 20=24.

Answer:

A. 20, 24, 20