Question 1

Which of the following statements best explains why the isotope carbon-14 is used in radiocarbon dating, while carbon-12 is not?

Accepted Answer

Carbon-14 has more neutrons than carbon-12, making it unstable and radioactive, allowing it to decay over time.

Question 2

A neutral atom of chlorine has 17 protons and 18 neutrons. What is its mass number and how many electrons does it have?

Accepted Answer

Mass number 35, 17 electrons

Question 3

Which of the following electron configurations violates Hund's Rule?

Accepted Answer

1s² 2s² 2p² (with both electrons paired in the same 2p orbital)

Question 4

Which element is expected to have the highest electronegativity?

Accepted Answer

Fluorine

Question 5

A student draws a Lewis structure for the carbonate ion (CO₃²⁻) with one double bond and two single bonds to oxygen. What concept explains why all C–O bonds in carbonate are experimentally found to be the same length?

Accepted Answer

Resonance structures

Question 6

Which of the following molecules is nonpolar despite containing polar bonds?

Accepted Answer

Carbon dioxide (CO₂)

Question 7

What is the formal charge on the nitrogen atom in the thiocyanate ion (NCS⁻), given the following Lewis structure: N≡C–S⁻?

Accepted Answer

0

Question 8

Which hybridization and geometry best describe the central atom in methane (CH₄)?

Accepted Answer

sp³, tetrahedral

Question 9

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

Accepted Answer

Hydrocarbons contain only carbon and hydrogen, while organic molecules contain carbon, hydrogen, and may include other elements.

Question 10

Which of the following functional groups is present in acetic acid (CH₃COOH)?

Accepted Answer

Carboxylic acid

Question 11

A molecule has the condensed electron configuration [Ne] 3s² 3p⁴. Which element is it, and how many valence electrons does it have?

Accepted Answer

Sulfur, 6 valence electrons

Question 12

Which of the following best explains why the oxygen atom in methanol (CH₃OH) forms two bonds?

Accepted Answer

Oxygen has six valence electrons and needs two more to complete its octet, so it forms two bonds.

Question 13

Which of the following statements about the Pauli Exclusion Principle is correct?

Accepted Answer

It states that no two electrons in the same atom can have the same set of four quantum numbers.

Question 14

Which of the following molecules is expected to be polar due to the presence of a lone pair on the central atom?

Accepted Answer

Nitrogen trifluoride (NF₃)

Question 15

A molecule has three electron groups around its central atom. What is its expected hybridization and molecular geometry?

Accepted Answer

sp², trigonal planar

Question 16

Which of the following best describes the process for drawing a correct Lewis structure for a molecule?

Accepted Answer

Count total valence electrons, connect atoms with single bonds, distribute remaining electrons to complete octets, form multiple bonds if necessary, and check formal charges.

Question 17

Which of the following ions is a cation?

Accepted Answer

Na⁺

Question 18

Which of the following best explains why fluorine is more electronegative than chlorine?

Accepted Answer

Fluorine is smaller in size, so its nucleus exerts a stronger pull on bonding electrons.

Question 19

Which of the following is a correct condensed electron configuration for potassium (Z = 19)?

Accepted Answer

[Ar] 4s¹

Question 20

Which of the following molecules contains a functional group that is responsible for the characteristic smell of vinegar?

Accepted Answer

Acetic acid (CH₃COOH)

General Chemistry: Atomic Structure, Bonding, and Molecular Properties

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