Q: A patient receives a dose of $250\ \mathrm{mg}$ of a medication. If the molar mass of the drug is $500\ \mathrm{g/mol}$, how many moles of the drug did the patient receive? (Report with correct significant figures.)

$5.0 \times 10^{-4}\ \mathrm{mol}$

Question 1

A student measures the mass of a metal cylinder as $45.67\ \mathrm{g}$ and its volume as $12.3\ \mathrm{cm}^3$. What is the density of the cylinder, reported with the correct number of significant figures?

Accepted Answer

$3.71\ \mathrm{g/cm}^3$

Question 2

Which of the following statements best describes the Law of Definite Proportions?

Accepted Answer

A compound always contains the same elements in the same proportion by mass.

Question 3

Which of the following is the correct electron configuration for a neutral sulfur atom ($Z=16$)?

Accepted Answer

$1s^2\ 2s^2\ 2p^6\ 3s^2\ 3p^4$

Question 4

A sample contains $3.01 	imes 10^{23}$ molecules of carbon dioxide ($\mathrm{CO}_2$). How many moles of $\mathrm{CO}_2$ are present?

Accepted Answer

$0.500$ moles

Question 5

Which of the following compounds is named correctly?

Accepted Answer

PCl$_5$: phosphorus pentachloride

Question 6

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from a metal to a nonmetal.

Question 7

Which of the following elements is isoelectronic with $\mathrm{Ne}$?

Accepted Answer

$\mathrm{F}^-$

Question 8

A radioactive isotope emits a beta particle. Which of the following correctly describes the change in the nucleus?

Accepted Answer

A neutron is converted into a proton.

Question 9

Which of the following molecules has a trigonal planar geometry according to VSEPR theory?

Accepted Answer

$\mathrm{BF}_3$

Question 10

A student converts $5.00$ miles to kilometers. (Given: $1\ \mathrm{mile} = 1.609\ \mathrm{km}$.) What is the answer with the correct number of significant figures?

Accepted Answer

$8.05\ \mathrm{km}$

Question 11

Which of the following statements is NOT part of Dalton’s atomic theory?

Accepted Answer

Atoms can be subdivided into protons, neutrons, and electrons.

Question 12

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between two atoms.

Question 13

How many valence electrons are present in a phosphorus atom ($Z=15$)?

Accepted Answer

5

Question 14

Which of the following is the correct Lewis symbol for a magnesium ion ($\mathrm{Mg}^{2+}$)?

Accepted Answer

$\mathrm{Mg}^{2+}$

Question 15

A compound contains $40.0\%$ carbon, $6.7\%$ hydrogen, and $53.3\%$ oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

$\mathrm{CH}_2\mathrm{O}$

Question 16

Which of the following best describes the difference between a molecule and an atom?

Accepted Answer

A molecule consists of two or more atoms chemically bonded together, while an atom is a single particle of an element.

Question 17

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine

Question 18

A neutral atom of calcium ($Z=20$) has how many core electrons?

Accepted Answer

18

Question 19

Which of the following is the correct name for $\mathrm{N}_2\mathrm{O}_5$?

Accepted Answer

Dinitrogen pentoxide

Question 20

A patient receives a dose of $250\ \mathrm{mg}$ of a medication. If the molar mass of the drug is $500\ \mathrm{g/mol}$, how many moles of the drug did the patient receive? (Report with correct significant figures.)

Accepted Answer

$5.0 	imes 10^{-4}\ \mathrm{mol}$

Intro to Chemistry Study Guide: Key Concepts and Skills

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