Calculating Average Atomic Mass

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.

Calculate the average atomic mass of silver.

• 106.38649amu
• 111.91896amu
• 107.8677amu
• 121

Tags

NGSS.HS-PS1-7

An element has two naturally occurring isotopes. One is 10.013 amu and is 19.9% abundant. The other is 11.01 amu and is 80.1% abundant. What is the average atomic mass? What element is it?

• 9.012, Beryllium
• 12.011, Carbon
• 6.941, Lithium
• 10.812, Boron