Stoichiometry Quiz

What is the charge of a proton?

• Variable

• Negative

• Neutral

• Positive

Which of the following particles is neutral?

• Positron

• Neutron

• Proton

• Electron

What is the nucleon number (A) of an atom?

• Total number of electrons

• Total number of protons and neutrons

• Total number of neutrons

• Total number of protons

If an atom has a proton number of 13 and a nucleon number of 27, how many neutrons does it have?

• 14

• 13

• 10

• 27

In a chemistry class, Aria is learning about isotopes. She comes across a notation that shows a number on the top left of an element's symbol. What does this number represent?

• Proton number

• Nucleon number

• Charge

• Electron number

What is the average atomic mass of magnesium if the isotopes are 24Mg, 25Mg, and 26Mg with respective abundances?

• 26.00 amu

• 25.00 amu

• 23.50 amu

• 24.33 amu

How do you calculate the relative atomic mass (Ar) of an element?

• Total mass of neutrons

• Total mass of protons

• Average of isotopes based on abundance

• Sum of all isotopes

In a chemistry lab, Anika is studying the properties of copper. She finds that the average atomic mass of copper is 63.5. To understand the composition better, she wants to know the proportion of 63Cu and 65Cu in her sample.

• 0.80 and 0.20

• 0.60 and 0.40

• 0.50 and 0.50

• 0.75 and 0.25

What defines isotopes of an element?

• Different chemical properties

• Same number of protons

• Different number of electrons

• Same number of neutrons

Liam is conducting an experiment in his physics lab to measure the mass of an electron. He finds several values in his reference materials. What is the mass of an electron in amu?

• 1.007 amu

• 0.511 amu

• 0.00055 amu

• 1.008 amu