D425 Introduction to Chemistry - Set 5 - Part 1

Correct Answer: Oxygen absence

Option b is correct because anaerobic conditions prevent oxidative decay, preserving organic materials for centuries in seafloor sediments effectively.
Option a is incorrect because deep ocean is cold, not hot; low temperature alone doesn't explain the preservation observed underwater.
Option c is incorrect because deep ocean is dark; lack of oxygen, not darkness, prevents decomposition of organic materials there.
Option d is incorrect because magnetism doesn't affect decomposition; oxygen availability determines whether organic decay occurs in marine environments.

Correct Answer: Organized protein sheets

Option b is correct because beta-sheet structures aligned along fiber axis provide remarkable strength while maintaining flexibility and elasticity.
Option a is incorrect because random coiling would create weak material; organized structure gives spider silk its exceptional strength properties.
Option c is incorrect because silk proteins don't contain metals; the strength comes from protein structure, not metallic reinforcement present.
Option d is incorrect because silk is primarily amorphous with organized regions; it's not crystalline but structured protein arrangement throughout.

Correct Answer: Extraction and reactions

Option b is correct because alcohol extracts compounds from wood while chemical reactions create new flavors and colors progressively.
Option a is incorrect because fermentation already occurred before barreling; aging involves chemical extraction and reactions, not microbial activity continuing.
Option c is incorrect because oak wood doesn't contain significant metals; organic compounds from wood provide flavor and color instead.
Option d is incorrect because proteins aren't formed during aging; existing wood compounds extract and react with alcohol over time.

Correct Answer: Improves nutrient availability

Option b is correct because neutral pH increases solubility of essential nutrients, making them accessible to plant roots effectively.
Option a is incorrect because lime provides calcium and carbonate, not nitrogen; it affects pH and mineral availability, not nitrogen content.
Option c is incorrect because lime reduces harmful aluminum solubility; it doesn't increase salt concentration that would harm plants growing.
Option d is incorrect because lime improves soil structure for better water retention, not reduction; it enhances growing conditions overall.

Correct Answer: Crystal structure similarity

Option b is correct because silver iodide's crystal structure mimics ice, providing nucleation sites for ice crystal formation effectively.
Option a is incorrect because magnetism doesn't influence ice formation; structural similarity to ice crystals triggers the nucleation process occurring.
Option c is incorrect because cloud seeding works in cold clouds; silver iodide doesn't heat clouds but provides crystallization templates instead.
Option d is incorrect because color is irrelevant to nucleation; crystal structure matching with ice enables the seeding effect achieved.

Correct Answer: Oxidation prevention

Option b is correct because removing oxygen prevents oxidative degradation that causes yellowing and brittleness in paper over time.
Option a is incorrect because nitrogen is inert and doesn't bleach; it prevents degradation rather than actively treating the documents.
Option c is incorrect because nitrogen and oxygen have similar densities; the purpose is chemical protection, not weight reduction achieved.
Option d is incorrect because nitrogen doesn't enhance colors; it prevents color loss by stopping oxidation reactions from occurring progressively.

Correct Answer: Nonpolar nature

Option b is correct because wax molecules are nonpolar hydrocarbons that repel polar water molecules, creating protective beading effect.
Option a is incorrect because waxes are neutral molecules without ionic charges; their nonpolar nature, not charge, repels water effectively.
Option c is incorrect because waxes are organic compounds without metals; they work through hydrophobic interactions, not metallic bonding present.
Option d is incorrect because applied wax forms an amorphous layer; water repellency comes from molecular properties, not crystal arrangement.

Correct Answer: Proteolytic breakdown

Option b is correct because bacterial enzymes break proteins into amino acids and peptides, creating complex flavor compounds progressively developing.
Option a is incorrect because cheese aging occurs in darkness; bacteria use fermentation and proteolysis, not photosynthesis for energy production.
Option c is incorrect because cheese flavors come from organic compounds; metal oxidation isn't involved in flavor development processes occurring.
Option d is incorrect because flavor development involves biochemical reactions producing dissolved compounds, not crystal formation in cheese matrix present.

Correct Answer: Nitrogen oxidation

Option b is correct because lightning's energy breaks nitrogen bonds, allowing oxidation to nitrates that dissolve in rainwater falling.
Option a is incorrect because lightning affects nitrogen, not carbon; carbon fixation occurs through photosynthesis, not atmospheric electrical discharge events.
Option c is incorrect because while lightning involves electrical energy, the fertilizer effect comes from nitrogen oxidation, not water splitting.
Option d is incorrect because oxygen is already in its reduced form in atmosphere; lightning oxidizes nitrogen, not reduces oxygen.

Correct Answer: Ion exchange strengthening

Option b is correct because replacing sodium with larger potassium ions creates compressive stress, strengthening the glass surface significantly.
Option a is incorrect because acid etching removes material and weakens glass; strengthening requires adding stress, not removing material present.
Option c is incorrect because scratch resistance comes from strengthened glass itself, not plastic coatings that would scratch more easily.
Option d is incorrect because metal plating would reduce transparency; ion exchange strengthens glass while maintaining optical clarity throughout the material.

Correct Answer: Vinegar or lemon

Option b is correct because weak acids dissolve copper oxides and carbonates, revealing clean copper metal underneath the tarnish.
Option a is incorrect because milk is nearly neutral and too weak to dissolve copper compounds; stronger acids are needed effectively.
Option c is incorrect because sugar water lacks acidity to dissolve copper tarnish; acid, not sweetness, cleans copper surfaces chemically.
Option d is incorrect because oil might shine but doesn't remove tarnish chemically; acid dissolution is required for true cleaning.

Correct Answer: Electron trap states

Option b is correct because electrons get trapped in higher energy states, slowly releasing photons as they return to ground state.
Option a is incorrect because phosphorescence involves electron transitions, not nuclear decay which would produce radiation, not visible light safely.
Option c is incorrect because glowing results from physical electron transitions, not ongoing chemical reactions creating new compounds continuously formed.
Option d is incorrect because phosphorescence emits visible light from electron transitions, not infrared heat radiation from thermal energy present.

Correct Answer: Carbonation reaction

Option b is correct because calcium hydroxide reacts with atmospheric carbon dioxide forming harder calcium carbonate throughout the structure progressively.
Option a is incorrect because while reinforcement might rust, concrete strengthening comes from carbonation of cement compounds, not iron oxidation.
Option c is incorrect because salt crystallization damages concrete; carbonation with atmospheric gases strengthens it over extended time periods naturally.
Option d is incorrect because ice formation causes cracking and damage; long-term strengthening comes from chemical carbonation reactions occurring slowly.

Correct Answer: Slower cooling rate

Option b is correct because oil cools steel more gradually than water, reducing stress and cracking while achieving desired hardness.
Option a is incorrect because oil cools slower than water; this controlled cooling prevents cracking from thermal stress, improving blade quality.
Option c is incorrect because oil has lower boiling point than water; the advantage is cooling rate control, not temperature difference.
Option d is incorrect because oil doesn't react with steel; it's a cooling medium providing controlled heat extraction rate physically.

Correct Answer: Rolling mill contact

Option b is correct because final rolling passes two sheets together; roller contact creates shiny side while sheet-to-sheet contact creates dull.
Option a is incorrect because both sides are pure aluminum without coatings; the difference comes from mechanical processing, not chemical treatment.
Option c is incorrect because both sides oxidize equally; the appearance difference results from manufacturing process, not oxidation variations present.
Option d is incorrect because aluminum foil isn't painted; the surface difference comes from mechanical rolling process, not applied coatings.

Correct Answer: Controlled evaporation

Option b is correct because gentle heating evaporates water while preserving volatile flavor compounds that give maple syrup distinctive taste.
Option a is incorrect because freezing would concentrate but not create the caramelized flavors developed during controlled heating and evaporation processes.
Option c is incorrect because maple syrup uses pure concentration without thickening agents; it's natural concentration through water removal only performed.
Option d is incorrect because fermentation would produce alcohol and change flavors; syrup production uses physical concentration, not biological processes.

Correct Answer: Chromium atoms

Option b is correct because chromium ions replacing aluminum in the crystal lattice absorb specific wavelengths producing red color observed.
Option a is incorrect because gold would produce different colors and isn't the impurity in rubies; chromium creates the red coloration.
Option c is incorrect because silver doesn't produce red color in aluminum oxide; chromium specifically causes ruby's characteristic red hue displayed.
Option d is incorrect because copper typically produces blue or green colors in minerals; chromium gives rubies their red color specifically.

Correct Answer: Pectin reinforcement

Option b is correct because calcium ions cross-link pectin molecules in cell walls, maintaining structural integrity and crispness during storage.
Option a is incorrect because calcium affects texture, not color; its role is structural reinforcement, not visual enhancement of pickles.
Option c is incorrect because calcium chloride doesn't add sweetness; it strengthens cell walls through pectin interactions, not flavor modification attempted.
Option d is incorrect because vegetables don't form new proteins during pickling; calcium strengthens existing pectin structures in cell walls present.

Correct Answer: Sodium chlorate

Option b is correct because sodium chlorate thermally decomposes into sodium chloride and oxygen gas when heated in emergency generators.
Option a is incorrect because ice produces water vapor when heated, not oxygen; chemical decomposition, not phase change, generates oxygen needed.
Option c is incorrect because carbon dioxide is the waste product of breathing; it doesn't decompose to provide oxygen for respiration.
Option d is incorrect because solid nitrogen would produce nitrogen gas, not oxygen; specific oxygen-containing compounds are required for generators.

Correct Answer: Particle fragmentation

Option b is correct because laser energy breaks large ink particles into fragments small enough for immune system removal naturally.
Option a is incorrect because ink doesn't evaporate through skin; it's broken into smaller pieces for biological removal, not vaporized away.
Option c is incorrect because the goal is removing ink, not changing color; fragmentation allows body to clear the particles progressively.
Option d is incorrect because tattoo inks aren't magnetic; laser energy mechanically fragments particles through rapid heating, not magnetic extraction performed.