If an element has 18 protons and 20 neutrons and 18 electrons,which expression correctly identifies the element?
A)argon-38
B)argon-18
C)argon-20
D)calcium-38
E)calcium-20

Question

Quizplus · Accepted Answer

The element is argon (Ar) because its atomic number, which is equal to the number of protons, is 18. The mass number is the sum of protons and neutrons, which is 38 (18 protons + 20 neutrons). Therefore, argon-38 is the correct identification.

If an Element Has 18 Protons and 20 Neutrons and 18