Q: Which of the following best defines Avogadro's number?

The number of atoms or molecules in one mole, $6.022 \times 10^{23}$.

Q: Which of the following is the correct relationship between moles, mass, and atomic mass for an element?

$\text{Moles} = \dfrac{\text{Mass (g)}}{\text{Atomic mass (g/mol)}}$

Question 1

Which of the following statements best describes the difference between metals and non-metals as found on the periodic table?

Accepted Answer

Metals are typically conductive, lustrous, and ductile, while non-metals are usually non-conductive, brittle, and not lustrous.

Question 2

Which of the following elements is an alkaline earth metal?

Accepted Answer

Magnesium ($Mg$)

Question 3

A sample of carbon contains $98.89\%$ $^{12}C$ (12.000 amu) and $1.11\%$ $^{13}C$ (13.0034 amu). What is the weighted average atomic mass of this sample?

Accepted Answer

$12.01$ amu

Question 4

Which of the following best defines Avogadro's number?

Accepted Answer

The number of atoms or molecules in one mole, $6.022 	imes 10^{23}$.

Question 5

If you have $10.0$ grams of aluminum ($Al$), how many atoms of $Al$ do you have? (Atomic mass of $Al = 26.98$ g/mol, Avogadro's number $= 6.022 	imes 10^{23}$)

Accepted Answer

$2.23 	imes 10^{23}$ atoms

Question 6

Which of the following is true about noble gases?

Accepted Answer

They are generally unreactive and do not tend to gain or lose electrons.

Question 7

A mass spectrometer is used to determine the atomic mass of an isotope. If the ratio of the mass of $^{13}C$ to $^{12}C$ is $1.0836129$, what is the mass of $^{13}C$ if $^{12}C$ is defined as $12$ amu?

Accepted Answer

$13.0034$ amu

Question 8

Which of the following best describes a group (or family) on the periodic table?

Accepted Answer

A vertical column of elements with similar chemical properties.

Question 9

Given $1000$ atoms of rhenium ($Re$), how many moles of rhenium do you have? (Avogadro's number $= 6.022 	imes 10^{23}$)

Accepted Answer

$1.66 	imes 10^{-21}$ moles

Question 10

Which of the following elements is most likely to form a $1^-$ anion?

Accepted Answer

Fluorine ($F$)

Question 11

A sample contains $0.5$ mm of the $204$ amu isotope, $10$ mm of the $206$ amu isotope, $8.5$ mm of the $207$ amu isotope, and $22$ mm of the $208$ amu isotope. Which isotope is most abundant in the sample?

Accepted Answer

$208$ amu

Question 12

Which of the following best explains why the atomic weight of carbon is listed as $12.01$ on the periodic table, even though no single atom of carbon has a mass of $12.01$ amu?

Accepted Answer

It is the weighted average of all naturally occurring isotopes of carbon.

Question 13

Which of the following is the correct relationship between moles, mass, and atomic mass for an element?

Accepted Answer

$	ext{Moles} = \dfrac{	ext{Mass (g)}}{	ext{Atomic mass (g/mol)}}$

Question 14

Which of the following elements is found in the second period of the periodic table?

Accepted Answer

Boron ($B$)

Question 15

If you have $0.371$ moles of aluminum ($Al$), how many atoms of $Al$ do you have? (Avogadro's number $= 6.022 	imes 10^{23}$)

Accepted Answer

$2.23 	imes 10^{23}$ atoms

Question 16

Which of the following is a property of alkali metals?

Accepted Answer

They form $1^+$ cations by losing one electron.

Question 17

A student claims that the atomic number of an element is the same as the number of neutrons in its nucleus. Is this correct?

Accepted Answer

No, the atomic number is the number of protons in the nucleus.

Question 18

Which of the following best describes the use of a mass spectrometer in chemistry?

Accepted Answer

It is used to measure the atomic or molecular masses of elements and compounds.

Question 19

If you have $1$ mole of marbles, how many marbles do you have?

Accepted Answer

$6.022 	imes 10^{23}$ marbles

Elements, Atomic Mass, Isotopes, and the Mole: Foundations of General Chemistry

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