Week 7 Review Quiz

Question 1

If an atom loses electrons in a redox reaction, we say this atom was oxidized.

When an atom undergoes a redox process and loses electrons, it is described as being oxidized. Oxidation always involves the loss of electrons, while reduction involves the gain of electrons. This principle is summarized by the acronym OIL RIG (Oxidation Is Loss, Reduction Is Gain).

Question 2

In the reaction CrO + H₂ → H₂O + Cr, the element being reduced is Cr.

In this reaction, chromium (Cr) undergoes reduction. Reduction occurs when an element gains electrons, leading to a decrease in its oxidation number. Chromium accepts electrons, thus being reduced in this chemical equation.

Question 3

The oxidizing agent in the reaction Fe³⁺ + V → Fe + V³⁺ is Fe³⁺.

Here, Fe³⁺ functions as the oxidizing agent, as it causes vanadium (V) to lose electrons and become oxidized. An oxidizing agent is the species that undergoes reduction while promoting oxidation in another substance.

Question 4

The molecule that is not a hydrocarbon is Methanol.

Hydrocarbons are organic molecules consisting only of carbon and hydrogen atoms. Methanol (CH₃OH), however, contains an oxygen atom, which disqualifies it from being a pure hydrocarbon.

Question 5

The molecules containing a triple bond are:

Molecules like pentyne and butyne belong to the alkyne family, characterized by carbon-to-carbon triple bonds.

Question 6

A key application of hydrocarbons is their use as fuel.

Hydrocarbons serve as the main component of fossil fuels such as natural gas, gasoline, and diesel. Their combustion releases energy, making them vital in power generation and transportation industries.

Question 7

The COOH group represents the carboxyl functional group.

The –COOH group is a defining feature of carboxylic acids, which are organic compounds essential in metabolic pathways such as the citric acid cycle.

Question 8

The type of hydrocarbon that contains a carbon-to-carbon double bond is an alkene.

Alkenes are hydrocarbons that feature at least one double bond between carbon atoms. These unsaturated compounds are commonly used in the production of plastics and other polymers.

Question 9

Examples of unsaturated hydrocarbons include:

Unsaturated hydrocarbons are molecules that have either double or triple bonds, making them chemically more reactive compared to saturated hydrocarbons.

Question 10

The name of the organic compound CH₃CH₂OCH₃ is ethyl methyl ether.

This molecule belongs to the ether group, which consists of compounds containing an oxygen atom bonded to two carbon groups. Ethyl methyl ether is an example of a simple ether.

Question 11

Match each of the following formulas and names (all numbers are subscripts):

(Note: The original matching content was missing, so this table illustrates common hydrocarbons and their names.)

Question 12

Molybdenum-99 decays by beta decay emission, resulting in an electron and Technetium-99.

During beta decay, a neutron transforms into a proton, releasing an electron (beta particle) and producing Technetium-99, a useful isotope in medical imaging.

Question 13

When Tin-126 undergoes electron capture, the mass number of the product remains 126.

In electron capture, the nucleus absorbs an electron, changing a proton into a neutron. Since no nucleons are lost, the mass number remains unchanged at 126.

Question 14

Sources of electromagnetic radiation include:

Electromagnetic radiation may originate from both natural and artificial sources, ranging from gamma rays in radioactive decay to X-rays in medical imaging.

Question 15

If a radioactive material has a half-life of 10 minutes, then after 30 minutes, 3 half-lives would occur.

After three half-lives, the material’s quantity would reduce to 1/8 of its original mass. Half-life concepts are crucial in nuclear chemistry and medical applications.

Question 16

A 60-gram sample of radioactive material with a half-life of 5 years will reduce to 15 grams after 10 years.

In two half-lives (10 years), the sample’s mass decreases from 60 g to 30 g (after 5 years), and then to 15 g (after 10 years).

Question 17

When Polonium-255 decays by positron emission, the product is Bismuth-255.

In positron emission (β⁺ decay), a proton converts into a neutron, releasing a positron and forming a new element, in this case, Bismuth-255.

Question 18

Examples of proteins include:

Proteins are essential biomolecules that act as biological catalysts (enzymes) and play a defensive role in the immune system (antibodies).

Question 19

The carbohydrate classified as a polysaccharide is starch.

Starch is a storage polysaccharide in plants, made up of long chains of glucose. It is a vital dietary carbohydrate for humans.

Question 20

Molecules that participate in the formation of fatty esters are:

Fatty acids combine with glycerol through esterification to form triglycerides, which are the main form of fat storage in the body.

Question 21

If a lipid is classified as a fat, it would be expected to:

Fats are generally saturated lipids, meaning they lack carbon-to-carbon double bonds and tend to remain solid at room temperature.

Question 22

A fragment of the coding strand of DNA reads as TAC-CGA-GAC-TAG.
The code of the template strand is ATG-GCT-CTG-ATC.

The template strand is complementary to the coding strand, ensuring accurate transcription into mRNA.

Question 23

Biomolecules that are part of the transcription process include:

In transcription, DNA serves as the template, while mRNA carries the genetic message to the ribosome for translation.

Question 24

The process in which a protein is synthesized from mRNA at the ribosomes is called translation.

Translation occurs in the ribosomes, where the genetic code in mRNA is decoded to assemble amino acids into polypeptide chains.

Question 25

The category of biological macromolecules that contains fats and oils is lipids.

Lipids include fats, oils, waxes, and steroids, playing structural, energy storage, and signaling roles.

Question 26

The level of protein structure that involves the interactions of multiple polypeptide strands to form complex structures is the quaternary level.

The quaternary structure is seen in proteins like hemoglobin, where multiple subunits work together to perform a biological function.

Question 27

The main role of enzymes in the body is to act as biological catalysts.

Enzymes accelerate biochemical reactions by lowering activation energy, making them essential for sustaining life processes such as digestion and metabolism.

References

OpenStax. (2016). Chemistry. OpenStax CNX. https://openstax.org/books/chemistry

Timberlake, K. C. (2018). General, organic, and biological chemistry: Structures of life (6th ed.). Pearson.

CHEM 120 Week 7 Review Quiz: Key Concepts and Questions

Zumdahl, S. S., & Zumdahl, S. A. (2019). Chemistry (10th ed.). Cengage Learning.