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 atomic weight of this element?

• 74.92 amu

• 24.97 amu

• 75.01 amu

• 74.51 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.
How many protons does this element have?

• 32
• 33
• 34
• no way to know

Tags

NGSS.MS-PS1-1

Calcium has three different isotopes. One has a mass of 35.00 amu; another has a mass of 41.00 amu; and another has a mass of 40.00 amu. Based on calcium's average atomic weight (look it up), which isotope is the most abundant of the three?

• 40.00 amu

• 41.00 amu

• 35.00 amu

• impossible to tell

Find the average atomic weight of an element where 4.35% of the atoms have a mass of 49.9461 amu, 83.79% have a mass of 51.9405 amu, 9.50% have a mass of 52.9407 amu, and 2.36% have a mass of 53.9389amu.

• 51.99 amu

• 52.19 amu

• 53.45 amu

• 17.33 amu

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

Tags

NGSS.MS-PS1-1

An isotope has three forms.  30% have a mass of 4 amu, 20% have a mass of 5 amu and 50% have a mass of 3 amu.  Average atomic mass will be closest to

• 2 amu
• 3 amu
• 4 amu
• 5 amu

Based on the table, calculate the average atomic mass of silver. (51.86% = 106.90509 amu; remaining % = 108.90470 amu)

• 106.38649amu

• 111.91896amu

• 107.8677amu

• 121

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

Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Based on nitrogen's average atomic weight (look it up), which isotope is the most abundant?

• Nitrogen-13

• Nitrogen-14

• Nitrogen-15

• Based on the information given, it cannot be determined

In a sample of atoms of an element, 12 atoms were found to have a mass of 11 amu, 8 atoms had a mass of 10 amu, and 5 atoms had a mass of 13 amu. What is the average atomic mass?

• 8.33 amu

• 92.33 amu

• 11.08 amu

• none of the above