Average Atomic Mass

4.35% of all X atoms have a mass of 39.946 amu. 83.79% have a mass of 41.941 amu, 9.50% have a mass of 42.941 amu, and 2.36% have a mass of 43.939 amu. What is the average atomic mass of atom X?

• 41.97 amu
• 42.19 amu
• 10.43 amu
• 40.04 amu

24.1% of all the isotopes of a an element have a mass of 75.23 amu, 48.7% have a mass of 74.61 amu, and 27.2% have a mass of 75.20 amu.
What is the average mass of this element?

• 74.92 amu
• 24.97 amu
• 75.01 amu
• 74.51 amu

Magnesium exists as three isotopes shown above. What is the average atomic mass?

• 18.39 amu

• 20.74 amu

• 22.56 amu

• 24.31 amu

Compute the average atomic mass for silicon:

• 27.977
• 28.09
• 28.976
• The average mass cannot be determined from provided information.

Atom 1 has Mass=12  Protons=6
Atom 2 has Mass= 14 Electrons=6
Are these atoms isotopes of each other or different elements?

• Different Elements - Mg & Si
• Different Elements - Ar & Ca
• Isotopes of Carbon
• Isotopes of Magnesium