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

An element has three different isotopes. One has a mass of 35.00 amu; another has a mass of 36.00  amu; and another has a mass of 38.00  amu. What is the average atomic mass of this element?

• 36.33 amu
• 37.00 amu
• 12.11 amu
• impossible to tell

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

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

Tags

NGSS.MS-PS1-1

What is the name of the atom pictured here?

• Nitrogen
• Nitrogen-15
• Nitrogen-7
• Nitrogen-8

Tags

NGSS.HS-PS1-8

Element X has two isotopes. If 54% of the element has an atomic mass of 49.6 amu, and 56% of the element has an atomic mass of 42.4 amu, the average atomic mass of element X is equal to which of the following?

• (0.54 x 49.6) + (0.56 x 42.4)

• (0.54 - 49.6) x (0.56 + 42.4)

• (0.54 + 49.6) x (0.56 + 42.4)