D425 Introduction to Chemistry - Set 3 - Part 2

Correct Answer: Fat migration

Option b is correct because cocoa butter separates and recrystallizes on surface when chocolate isn't properly tempered initially.
Option a is incorrect because chocolate's low water activity prevents bacterial growth; bloom is a physical, not biological phenomenon.
Option c is incorrect because chocolate repels water; bloom results from fat separation, not moisture absorption from environment.
Option d is incorrect because fermentation requires water and microorganisms; bloom is fat crystallization, not a fermentation process.

Correct Answer: Chemical stability

Option b is correct because CFCs resist breakdown in lower atmosphere, allowing transport to stratosphere before decomposing there.
Option a is incorrect because density affects ground-level concentration but doesn't determine atmospheric transport or survival time aloft.
Option c is incorrect because color doesn't affect atmospheric lifetime; chemical stability determines how long molecules persist environmentally.
Option d is incorrect because magnetic properties don't influence atmospheric chemistry or the ability to reach stratospheric altitudes.

Correct Answer: Improved specificity

Option b is correct because single enantiomers provide specific biological activity without potential side effects from other forms.
Option a is incorrect because enantiomers have identical physical properties including color; the difference is biological activity only.
Option c is incorrect because enantiomers have identical molecular weight; separation doesn't change the mass of active ingredient.
Option d is incorrect because organic drug molecules aren't metallic; chirality affects biological, not metallic properties of compounds.

Correct Answer: Metabolic breakdown

Option b is correct because bacteria convert pollutants into harmless products through enzymatic metabolism, not just physical removal.
Option a is incorrect because reproduction speed helps establish populations but metabolic capability is the key cleaning mechanism utilized.
Option c is incorrect because bacterial color is irrelevant to remediation; their metabolic pathways accomplish the actual cleanup work.
Option d is incorrect because bacteria are microscopic; their small size allows access to contaminated areas, not large size.

Correct Answer: Continuous fuel requirement

Option b is correct because fuel cells need constant fuel supply while batteries store all reactants internally from manufacturing.
Option a is incorrect because both fuel cells and batteries come in various sizes; operational principle, not size, differs.
Option c is incorrect because color doesn't determine function; the need for external fuel distinguishes fuel cells from batteries.
Option d is incorrect because shape varies for both technologies; the fundamental difference is fuel supply requirement, not geometry.

Correct Answer: Phase transformation

Option b is correct because reversible martensitic phase transformation allows atomic rearrangement back to the memorized crystal structure.
Option a is incorrect because shape memory involves crystal structure changes, not electron loss which would change chemical properties.
Option c is incorrect because color change might accompany phase transformation but isn't the mechanism for shape recovery itself.
Option d is incorrect because density changes are minimal; the key is crystal structure transformation, not significant density variation.

Correct Answer: Anaerobic metabolism

Option b is correct because anaerobic pathways convert sugars to products like organic acids without needing oxygen present.
Option a is incorrect because fermentation doesn't require light; it's a metabolic process that occurs in darkness effectively.
Option c is incorrect because fermentation involves biochemical reactions, not nuclear transformations which would change elements themselves fundamentally.
Option d is incorrect because magnetic sensing doesn't relate to fermentation; metabolic enzymes drive the chemical conversions occurring.

Correct Answer: High pressure and temperature

Option b is correct because extreme pressure and temperature overcome the energy barrier for carbon's structural transformation occurring.
Option a is incorrect because low pressure favors graphite formation; diamond requires extremely high pressure to form and stabilize.
Option c is incorrect because light exposure doesn't affect diamond formation; pressure and temperature are the critical controlling factors.
Option d is incorrect because magnetic fields don't drive carbon phase transitions; mechanical and thermal energy are required instead.

Correct Answer: Optical interference

Option b is correct because microscopic structures create interference patterns that change color with viewing angle for authentication.
Option a is incorrect because temperature-sensitive inks would change unpredictably with environmental conditions, not providing reliable security consistently.
Option c is incorrect because magnetic inks are detected by machines, not visual inspection for security verification purposes typically.
Option d is incorrect because radioactive materials would be hazardous and impractical for currency that people handle daily.

Correct Answer: Halogen content

Option b is correct because chlorine and bromine atoms catalyze ozone destruction, while fluorine-only compounds don't deplete ozone.
Option a is incorrect because boiling point affects refrigeration efficiency but doesn't determine ozone depletion potential directly at all.
Option c is incorrect because molecular weight influences physical properties but ozone depletion depends on chemical composition, particularly halogens.
Option d is incorrect because physical state at room temperature doesn't determine atmospheric chemistry or ozone interaction potential.

Correct Answer: Entropy decrease

Option b is correct because separating mixed salt and water decreases entropy, requiring energy input by thermodynamic laws.
Option a is incorrect because color differences don't determine energy requirements; thermodynamic principles govern separation energy needs fundamentally.
Option c is incorrect because volume changes don't explain the fundamental energy requirement for overcoming mixing entropy effectively.
Option d is incorrect because temperature changes are effects, not causes of the energy requirement for separation processes.

Correct Answer: Molecular identification

Option b is correct because mass spectrometry provides unique molecular fingerprints allowing definitive identification of trace explosive compounds.
Option a is incorrect because display brightness doesn't affect detection capability; molecular identification accuracy is the key advantage.
Option c is incorrect because sound levels are irrelevant to analytical performance; the technique's value is identification capability.
Option d is incorrect because portable mass spectrometers exist; the technique's value is sensitivity and specificity, not size.

Correct Answer: Acid-catalyzed hydrolysis

Option b is correct because acids from manufacturing or pollution catalyze cellulose breakdown, causing yellowing and brittleness over time.
Option a is incorrect because paper contains little metal; cellulose degradation, not metal oxidation, causes deterioration primarily observed.
Option c is incorrect because salt formation isn't the primary degradation mechanism; acid-catalyzed reactions break down cellulose structure.
Option d is incorrect because while gases may contribute acids, the degradation mechanism is hydrolysis, not gas absorption itself.

Correct Answer: Hydroxyapatite crystals

Option b is correct because organized hydroxyapatite crystals provide hardness but dissolve in acids, causing cavity formation potentially.
Option a is incorrect because enamel is a calcium phosphate mineral, not carbon; diamond-like hardness comes from crystal organization.
Option c is incorrect because iron would cause discoloration and isn't the primary component of dental enamel structure naturally.
Option d is incorrect because silicon dioxide is found in glass and sand, not biological materials like tooth enamel.

Correct Answer: Low-temperature effectiveness

Option b is correct because ethylene oxide kills microorganisms at room temperature, preserving heat-sensitive plastics and electronics intact.
Option a is incorrect because ethylene oxide is colorless; its value is low-temperature sterilization, not any visual property.
Option c is incorrect because density doesn't determine sterilization effectiveness; the ability to kill at low temperature matters.
Option d is incorrect because ethylene oxide is an organic compound, not metallic; its reactivity provides sterilization capability achieved.

Correct Answer: Heat sensitivity

Option b is correct because some vitamins decompose at cooking temperatures while others have stable molecular structures throughout.
Option a is incorrect because color doesn't determine thermal stability; molecular structure and bond strength determine heat resistance levels.
Option c is incorrect because vitamins are molecules in solution, not crystals; thermal stability depends on chemical structure present.
Option d is incorrect because vitamins aren't magnetic; their stability depends on molecular structure, not magnetic properties ever possessed.

Correct Answer: Polymer bridging

Option b is correct because polymer chains bridge microcracks and provide flexibility, preventing crack propagation through concrete matrix.
Option a is incorrect because color is aesthetic; crack resistance comes from mechanical properties, not appearance or pigmentation added.
Option c is incorrect because while density might change, the key benefit is mechanical reinforcement, not weight reduction achieved.
Option d is incorrect because concrete components aren't magnetic; polymers provide mechanical, not magnetic reinforcement to the structure.

Correct Answer: Surface coverage

Option b is correct because foam creates a blanket preventing oxygen access and vapor release, extinguishing fires effectively.
Option a is incorrect because foam is actually lighter than water; its effectiveness comes from coverage, not weight primarily.
Option c is incorrect because color doesn't affect firefighting ability; the barrier properties of foam provide fire suppression capability.
Option d is incorrect because foam is a dispersion, not solid; its fluid nature allows spreading and coverage needed.

Correct Answer: Degradation kinetics

Option b is correct because controlled polymer breakdown rates determine drug release speed, providing sustained therapeutic levels maintained.
Option a is incorrect because color is for identification; drug release depends on polymer chemistry, not visual appearance factors.
Option c is incorrect because metals would be incompatible with many drugs; polymer degradation, not metals, controls release rates.
Option d is incorrect because implants are typically amorphous polymers; controlled degradation, not crystal shape, determines release profiles achieved.

Correct Answer: Oxidation state changes

Option b is correct because heating changes metal ion oxidation states within gems, altering light absorption and color.
Option a is incorrect because heat treatment works internally; it doesn't involve adding surface coatings or external materials applied.
Option c is incorrect because heat treatment doesn't significantly change gem size; color enhancement occurs through electronic changes internally.
Option d is incorrect because density remains essentially constant; the color change results from electronic, not structural modifications occurring.