CHEM 120 Week 7 Review Quiz: Key Concepts and Questions

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Chamberlain University

CHEM-120 Intro to General, Organic & Biological Chemistry

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Date

Week 7 Review Quiz

Question 1

If an atom loses electrons in a redox reaction, we say this atom was:
Answer: Oxidized.
When an atom loses electrons, it undergoes oxidation. This loss increases the atom’s oxidation state and typically occurs when the atom reacts with an oxidizing agent. For example, in the reaction of sodium with chlorine, sodium loses an electron to form Na⁺, indicating oxidation.

Question 2

In the reaction CrO + H₂ → H₂O + Cr, the element being reduced is:
Answer: Chromium (Cr).
In this reaction, chromium gains electrons, thereby undergoing a reduction process. Reduction is identified by a decrease in the oxidation number of the atom involved.

Question 3

What is the oxidizing agent in the reaction Fe³⁺ + V → Fe + V³⁺?
Answer: Fe³⁺.
An oxidizing agent causes oxidation in another species by accepting electrons. Here, Fe³⁺ accepts electrons from vanadium (V), becoming Fe, and thus acts as the oxidizing agent.

Question 4

Which of the following molecules is not a hydrocarbon?
Answer: Methanol.
Hydrocarbons consist solely of hydrogen and carbon atoms. Methanol (CH₃OH) contains an oxygen atom, making it an alcohol, not a pure hydrocarbon.

Question 5

Which of the following molecules contains a triple bond? Select all that apply:

Molecule	Contains Triple Bond?
Pentyne	Yes
Butyne	Yes

Both pentyne and butyne are alkynes, a class of hydrocarbons with at least one carbon–carbon triple bond.

Question 6

A key application of hydrocarbons is:
Answer: Fuel.
Hydrocarbons are widely used as fuels because they release significant amounts of energy upon combustion. Examples include gasoline, diesel, and natural gas.

Question 7

The COOH group represents which functional group?
Answer: Carboxyl group.
The carboxyl functional group is characteristic of carboxylic acids and plays a key role in organic reactions such as esterification.

Question 8

This type of hydrocarbon contains a carbon-to-carbon double bond:
Answer: Alkene.
Alkenes are unsaturated hydrocarbons characterized by at least one C=C double bond, which influences their chemical reactivity.

Question 9

Which of the following would be classified as unsaturated hydrocarbons? Select all that apply.

Molecule	Classification
CH₂=CH₂	Alkene (unsaturated)
Propyne	Alkyne (unsaturated)

Unsaturated hydrocarbons contain double or triple bonds, which allow them to participate in addition reactions.

Question 10

The name of the organic compound CH₃CH₂OCH₃ would be:
Answer: Ethyl methyl ether.
This is an ether, characterized by an oxygen atom linking two alkyl groups—in this case, ethyl and methyl groups.

Question 11

Match each of the following formulas and names. Assume all numbers are subscripts.

CHEM 120 Week 7 Review Quiz: Key Concepts and Questions

Formula	Name
CH₄	Methane
C₂H₆	Ethane
C₂H₄	Ethene
C₂H₂	Ethyne

Question 12

Molybdenum-99 decays by beta decay emission, resulting in an electron and:
Answer: Technetium-99.
During beta decay, a neutron converts to a proton, emitting an electron (beta particle) and producing a new element with an atomic number increased by one.

Question 13

Tin-126 undergoes electron capture. What will be the mass number of the product of this decay?
Answer: 126.
In electron capture, a proton is converted into a neutron without changing the mass number. Only the atomic number decreases by one.

Question 14

Which of the below would be considered sources of electromagnetic radiation? Select all that apply.

Source	Electromagnetic Radiation?
X-ray emitter	Yes
Gamma decay	Yes

Both X-rays and gamma rays are high-energy electromagnetic waves.

Question 15

How many half-lives would occur after 30 minutes if a radioactive material has a half-life of 10 minutes?
Answer: 3 half-lives.
Thirty minutes divided by a 10-minute half-life equals three half-life periods.

Question 16

A 60 gram sample of a radioactive material has a half-life of 5 years. After 10 years, how many grams of the original radioactive material will remain?
Answer: 15 grams.

Calculation:

• After first 5 years: 60 g → 30 g
• After next 5 years: 30 g → 15 g

Question 17

When polonium-255 decays by positron emission, what is the product?
Answer: Bismuth-255.
Positron emission converts a proton into a neutron, reducing the atomic number by one without changing the mass number.

Question 18

Which of the following examples are proteins? Select all that apply.

Biomolecule	Protein?
Enzymes	Yes
Antibodies	Yes

Proteins serve diverse biological functions, including catalysis and immune defense.

Question 19

Choose the carbohydrate that is classified as a polysaccharide.
Answer: Starch.
Polysaccharides are long chains of monosaccharide units. Starch is a major energy-storage polysaccharide in plants.

Question 20

Which of the following molecules participate in the formation of fatty ester? Select all that apply.

Molecule	Role in Ester Formation
Fatty acids	Provide carboxyl group
Glycerol	Provides hydroxyl group

Fatty esters, such as triglycerides, form through esterification reactions between glycerol and fatty acids.

Question 21

If a lipid is classified as a fat, I would expect it to: (select all that apply)

Property	Present in Fats?
Solid at room temperature	Yes
No C=C double bonds	Yes

Fats are typically saturated lipids, which lack double bonds and remain solid at room temperature.

Question 22

A fragment of the coding strand of DNA reads in part as TAC-CGAGAC-TAG. The code of the template strand would be:
Answer: ATG-GCT-CTG-ATC.
The template strand is complementary to the coding strand, with base pairing rules: A↔T and C↔G.

Question 23

Select the biomolecules that are a part of the transcription process. Select all that apply.

Biomolecule	Role in Transcription
mRNA	Carries genetic code
DNA	Template for mRNA

Question 24

What is the term for the process in which a protein is synthesized from mRNA at the ribosomes?
Answer: Translation.
Translation is the process of decoding mRNA to assemble amino acids into a polypeptide chain.

Question 25

Which of the categories of biological macromolecules below contains fat and oils?
Answer: Lipids.
Lipids are a diverse group of hydrophobic molecules, including fats, oils, waxes, and certain vitamins.

Question 26

The level of protein structure that involves the interactions of multiple polypeptide strands to form more complex structures:
Answer: Quaternary structure.
This level of protein structure is seen in proteins like hemoglobin, where multiple subunits combine to function.

Question 27

What is the main role of enzymes in the body?
Answer: Act as biological catalysts.
Enzymes speed up biochemical reactions by lowering activation energy, making life-sustaining reactions possible.

References

Brown, T. L., LeMay, H. E., Bursten, B. E., & Murphy, C. (2018). Chemistry: The central science (14th ed.). Pearson.

Nelson, D. L., & Cox, M. M. (2021). Lehninger principles of biochemistry (8th ed.). W.H. Freeman.

CHEM 120 Week 7 Review Quiz: Key Concepts and Questions

Zumdahl, S. S., & Zumdahl, S. A. (2020). Chemistry (11th ed.). Cengage Learning.