Question 1

Which of the following best describes the difference between a Lewis structure and a line-bond (skeletal) structure for organic molecules?

Accepted Answer

A Lewis structure shows all atoms and electrons, while a line-bond structure omits hydrogen atoms bonded to carbons and lone pairs.

Question 2

Which of the following electron configurations correctly represents the ground state of a carbon atom?

Accepted Answer

$1s^2\ 2s^2\ 2p^2$

Question 3

Using VSEPR theory, what is the expected bond angle in a molecule with a tetrahedral geometry, such as methane ($CH_4$)?

Accepted Answer

$109.5^\circ$

Question 4

Which of the following statements about resonance structures is correct?

Accepted Answer

Resonance structures differ only in the placement of electrons, not the arrangement of atoms.

Question 5

Which of the following bonds is expected to be the shortest?

Accepted Answer

$C \equiv C$ (carbon-carbon triple bond)

Question 6

Which of the following is a correct statement about the relationship between bond strength and bond length?

Accepted Answer

Shorter bonds are generally stronger than longer bonds.

Question 7

Which of the following is the best description of a nucleophile in organic chemistry?

Accepted Answer

A nucleophile is an electron-rich species that donates a pair of electrons to an electrophile.

Question 8

Which of the following functional groups is present in both esters and carboxylic acids?

Accepted Answer

A carbonyl group ($C=O$)

Question 9

According to the Bronsted-Lowry definition, which of the following is a base?

Accepted Answer

A species that accepts a proton ($H^+$)

Question 10

Which of the following best explains why the $O-H$ bond in water is polar?

Accepted Answer

Oxygen is more electronegative than hydrogen, creating a partial negative charge on oxygen and a partial positive charge on hydrogen.

Question 11

Which of the following molecules is expected to have a net dipole moment?

Accepted Answer

$CH_3Cl$

Question 12

Which of the following statements about molecular orbitals is correct?

Accepted Answer

A bonding molecular orbital results from constructive overlap of atomic orbitals and is lower in energy than the original atomic orbitals.

Question 13

Which of the following is the correct order of acidity (from strongest to weakest acid) for the following compounds: acetic acid, ethanol, and water?

Accepted Answer

Acetic acid $>$ water $>$ ethanol

Question 14

Which of the following factors increases the acidity of a compound?

Accepted Answer

Increased resonance stabilization of the conjugate base

Question 15

A molecule has the following resonance structures. Which is the major contributor?

Accepted Answer

The structure in which all atoms have complete octets and the negative charge is on the most electronegative atom.

Question 16

Which of the following best describes the hybridization of the central carbon atom in ethene ($C_2H_4$)?

Accepted Answer

$sp^2$

Question 17

Which of the following statements about electrophiles is correct?

Accepted Answer

Electrophiles are electron-deficient species that accept electron pairs.

Question 18

Which of the following best explains why $NH_3$ is a stronger base than $H_2O$?

Accepted Answer

Nitrogen is less electronegative than oxygen, so it holds its lone pair less tightly and is more willing to donate it.

Question 19

Which of the following is the correct electron configuration for the oxygen atom in its ground state?

Accepted Answer

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

Question 20

Which of the following statements about the relationship between $pK_a$ and acid strength is correct?

Accepted Answer

A lower $pK_a$ value indicates a stronger acid.

Organic Chemistry Exam 1 Study Guide: Core Concepts and Skills

Study Guide - Practice Questions