What are the three main constituents of an atom?

• Protons, neutrons, and electrons

• Protons, neutrons, and photons

• Electrons, photons, and quarks

• Neutrons, quarks, and electrons

How many protons does an oxygen atom have?

• 26

• 6

• 8

• 11

What is the atomic mass of sodium?

• 23

• 56

• 16

• 11

Why is the atomic mass of chlorine not a whole number?

• It is a synthetic element

• It has an unstable nucleus

• It is an average of two isotopes

• It contains extra electrons

What is the exact atomic mass of the most common carbon isotope?

• 11.99

• 12.50

• 12.00

• 12.01