Question 1

Which of the following electron configurations correctly represents the ground state of a neutral sulfur atom ($Z = 16$)?

Accepted Answer

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

Question 2

Which of the following best explains why the first ionization energy of sodium ($Na$) is much lower than that of magnesium ($Mg$)?

Accepted Answer

Sodium has a lower effective nuclear charge ($Z_{eff}$) than magnesium, making it easier to remove its outermost electron.

Question 3

Which of the following ions is isoelectronic with argon ($Ar$)?

Accepted Answer

$Cl^-$

Question 4

Which of the following statements about paramagnetism and diamagnetism is correct?

Accepted Answer

A paramagnetic substance has one or more unpaired electrons and is attracted to a magnetic field.

Question 5

Which of the following correctly describes the trend in atomic radius across a period from left to right?

Accepted Answer

Atomic radius decreases due to increasing effective nuclear charge.

Question 6

Given the following combustion data: 1.00 g of a compound yields 1.47 g $CO_2$ and 0.60 g $H_2O$. What is the empirical formula of the compound?

Accepted Answer

$CH_2O$

Question 7

Which of the following is the correct name for $Fe_2O_3$?

Accepted Answer

Iron(III) oxide

Question 8

Which of the following statements about the periodic trends of ionization energy is correct?

Accepted Answer

Ionization energy increases across a period and decreases down a group.

Question 9

Which of the following molecules is polar, based on its Lewis structure and molecular geometry?

Accepted Answer

$NH_3$

Question 10

What is the bond angle in a molecule with tetrahedral electron geometry, such as methane ($CH_4$)?

Accepted Answer

$109.5^\circ$

Question 11

Which of the following best explains why $O_2$ is paramagnetic?

Accepted Answer

$O_2$ has two unpaired electrons in its molecular orbital configuration.

Question 12

Which of the following is the correct Lewis structure for $CO_2$?

Accepted Answer

O=C=O, with each oxygen atom having two lone pairs.

Question 13

A sample contains 0.50 mol of $NaCl$. What is the mass of the sample? ($Na = 22.99\ g/mol$, $Cl = 35.45\ g/mol$)

Accepted Answer

$29.22\ g$

Question 14

Which of the following best describes the relationship between electronegativity and bond polarity?

Accepted Answer

The greater the difference in electronegativity between two atoms, the more polar the bond.

Question 15

Which of the following molecules violates the octet rule?

Accepted Answer

$BF_3$

Question 16

What is the molecular geometry of $SF_6$ according to the VSEPR model?

Accepted Answer

Octahedral

Question 17

Which of the following best explains the trend in electron affinity across a period?

Accepted Answer

Electron affinity becomes more negative (increases) across a period due to increasing nuclear charge.

Question 18

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

Accepted Answer

$CH_2O$

Question 19

Which of the following best describes the bond in $N_2$?

Accepted Answer

A triple bond consisting of one sigma and two pi bonds.

Question 20

Which of the following statements about resonance is correct?

Accepted Answer

Resonance structures represent delocalized electrons within a molecule that cannot be described by a single Lewis structure.

General Chemistry Exam 2 Study Guide: Atomic Structure, Bonding, and Chemical Formulas

Study Guide - Practice Questions