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

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. Which isotope is the most abundant of the three? Hint: find the AAM on your periodic table.

• 40.00 amu
• 41.00 amu
• 35.00 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

Tags

NGSS.MS-PS1-1

Calculate the average atomic mass of silver.

• 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. First, calculate the average atomic mass. Then, use your periodic table to identify the element based on its AAM.

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

Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Which isotope is the most abundant?

• Nitrogen-13
• Nitrogen-14
• Nitrogen-15
• Based on the information given, it cannot be determined

Oxygen has 8 protons. What is oxygen's atomic number?

• 16
• 8
• 15.999
• 0

Tags

NGSS.MS-PS1-1

What is true about a neutral atom?

• The number of protons equal the number of neutrons
• The number of protons equal the number of electrons
• The number of neutrons equal the number of electrons
• The number of protons, neutrons, and electrons are all different

Tags

NGSS.MS-PS1-1

The  mass of an atom is located  in the ___________ and the volume of an atom is made of the ____________

• electron cloud, nucleus
• electron cloud, energy levels
• nucleus, electron cloud
• nucleus, neutrons

Tags

NGSS.MS-PS1-1

If X is the symbol for an element, which of the following two symbols represent    isotopes of the same element?     I. ⁷⁷₃₅X  II. ⁷⁷₃₃X  III. ⁸¹₃₇X  IV. ⁸¹₃₅ X

• I and II
• III and IV
• I and IV
• I and III

Tags

NGSS.HS-PS1-8