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OpenStem
@openstem · Joined Jul 2026
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Quiz6 questions
Why is cotton comfortable to wear on a hot day?
AIt is naturally fire-resistantBIt is breathable and absorbs moisture wellCIt dries faster than any other fiberDIt never wrinkles
Chemistry · L2 · Natural and Synthetic Fibers
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Chemistry · L2 · Natural and Synthetic FibersQuiz6 questions
Why do you need two DIFFERENT metals to make a simple battery instead of two pieces of the same metal?
ATwo different metals look better togetherBDifferent metals hold onto their tiny charged particles with different strength, which creates a push for charge to flowCYou need two different metals so the battery doesn't get too hotDOnly two different metals can touch an electrolyte at once
Chemistry · L2 · How Batteries Work
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Chemistry · L2 · How Batteries WorkQuiz6 questions
What does photosynthesis produce?
ACarbon dioxide and waterBGlucose and oxygenCNitrogen and waterDSoot and smoke
Chemistry · L2 · The Carbon Cycle
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Chemistry · L2 · The Carbon CycleQuiz6 questions
What is the chemical reaction that makes soap from a fat and lye called?
ANeutralizationBCombustionCSaponificationDFermentation
Chemistry · L2 · How Soap Is Made — Saponification
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Chemistry · L2 · How Soap Is Made — SaponificationQuiz5 questions
Why does salting meat help stop it from spoiling?
AThe salt directly destroys the DNA inside bacteria and mould cellsBA high salt concentration draws water out of microbe cells, drying them outCSalt raises the temperature of the meat enough to kill microbesDSalt reacts chemically with the meat to seal out all air
Chemistry · L2 · The Chemistry of Food Preservation
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Chemistry · L2 · The Chemistry of Food PreservationQuiz5 questions
What makes a dissolved substance an "electrolyte"?
AIt changes the colour of the waterBIt splits into charged ions that let the solution conduct electricityCIt always makes the water taste sweetDIt stops the water from freezing
Chemistry · L2 · Electrolytes and Sports Drinks
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Chemistry · L2 · Electrolytes and Sports DrinksQuiz5 questions
What kind of reaction is shown?
ANucleophilic substitutionBElectrophilic additionCFree-radical chain reactionDAcid–base neutralisation
Chemistry · L3 · Reactions and Structures — 5 Q
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Chemistry · L3 · Reactions and Structures — 5 QQuiz5 questions
Which subatomic particle has a negative charge and is found outside the nucleus, in the electron shells?
AProtonBNeutronCElectronDNucleus
Chemistry · L3 · Atomic Structure & Electron Configuration Quiz
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Chemistry · L3 · Atomic Structure & Electron Configuration QuizQuiz6 questions
What best explains why atomic radius decreases across a period?
AMore protons pull on the same outer shell, drawing it in tighterBA new electron shell is added at each stepCShielding from inner electrons increases sharplyDElectrons begin pairing up and repelling each other more
Chemistry · L3 · Periodic Trends — 6 Q
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Chemistry · L3 · Periodic Trends — 6 QQuiz6 questions
Sodium reacts with chlorine to form sodium chloride. What type of bond forms, and why?
ACovalent — both atoms share electrons equallyBIonic — sodium (a metal) transfers an electron to chlorine (a non-metal)CMetallic — both atoms release electrons into a shared seaDNo bond forms — sodium and chlorine repel each other
Chemistry · L3 · Ionic and Covalent Bonding — 6 Q
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Chemistry · L3 · Ionic and Covalent Bonding — 6 QQuiz6 questions
According to VSEPR theory, why do electron pairs around a central atom arrange the way they do?
AThey repel each other and spread out to be as far apart as possibleBThey attract each other and cluster together on one sideCTheir arrangement is random and unpredictableDThey arrange based on the atomic mass of the central atom
Chemistry · L3 · Molecular Geometry & VSEPR — 6 Q
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Chemistry · L3 · Molecular Geometry & VSEPR — 6 QQuiz5 questions
What does 'one mole' of a substance mean?
AExactly 6.02 × 10²³ particles of that substanceBExactly one gram of that substanceCOne atom of that substanceDThe volume the substance occupies at room temperature
Chemistry · L3 · Stoichiometry & the Mole — 5 Q
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Chemistry · L3 · Stoichiometry & the Mole — 5 QQuiz5 questions
According to Boyle's Law, if you compress a gas to half its original volume at constant temperature, what happens to its pressure?
AIt doublesBIt halvesCIt stays the sameDIt quadruples
Chemistry · L3 · Gas Laws — 5 Q
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Chemistry · L3 · Gas Laws — 5 QQuiz5 questions
What does the 'equivalence point' of an acid–base titration mean?
AThe point where the indicator first changes colour, whatever the pHBThe point where moles of acid added exactly equal moles of base addedCThe point where the solution's temperature stops changingDThe point where the burette is exactly half empty
Chemistry · L3 · Acid–Base Titration — 5 Q
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Chemistry · L3 · Acid–Base Titration — 5 QQuiz5 questions
80 g of water is heated from 15 °C to 65 °C. Using c = 4.18 J/(g·°C), how much heat energy was transferred?
A16.7 kJB21.7 kJC8.4 kJD1.67 kJ
Chemistry · L3 · Thermochemistry Basics Quiz
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Chemistry · L3 · Thermochemistry Basics QuizQuiz6 questions
Which pair of conditions must BOTH be true for a collision between reactant particles to cause a reaction?
AEnough energy to clear the activation energy, AND the correct orientationBThe particles must be the same size and the same colourCThe temperature must be above 100 °C and the pressure must be highDThe particles must collide more than once
Chemistry · L3 · Reaction Rates & Kinetics — 6 Q
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Chemistry · L3 · Reaction Rates & Kinetics — 6 QQuiz5 questions
What best describes a system at dynamic equilibrium?
AThe forward and reverse reaction rates are equalBThe forward reaction has stopped completelyCThe amounts of reactant and product are equalDThe reverse reaction has stopped completely
Chemistry · L3 · Chemical Equilibrium & Le Chatelier's Principle — 5 Q
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Chemistry · L3 · Chemical Equilibrium & Le Chatelier's Principle — 5 QQuiz5 questions
In the reaction Mg + 2H⁺ → Mg²⁺ + H₂, which species is oxidized?
AMagnesiumBHydrogen ionsCBoth are reducedDNeither — this isn't a redox reaction
Chemistry · L3 · Redox & Electrochemistry — 5 Q
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Chemistry · L3 · Redox & Electrochemistry — 5 QQuiz6 questions
What family does this molecule belong to, and what feature tells you?
AAlkane — only single bondsBAlkene — a C=C double bondCAlcohol — an –OH groupDCarboxylic acid — a –COOH group
Chemistry · L3 · Organic Chemistry: Functional Groups & Naming — 6 Q
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Chemistry · L3 · Organic Chemistry: Functional Groups & Naming — 6 QQuiz5 questions
Which particle is emitted during alpha decay?
AElectronBHelium nucleus (2 protons + 2 neutrons)CGamma ray photonDA single neutron
Chemistry · L3 · Nuclear Chemistry — 5 Q
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Chemistry · L3 · Nuclear Chemistry — 5 QQuiz5 questions
What does molarity (M) measure?
AMoles of solute per litre of solutionBGrams of solute per litre of solventCThe temperature at which a solution boilsDThe total mass of the solution
Chemistry · L3 · Solutions & Molarity — 5 Q
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Chemistry · L3 · Solutions & Molarity — 5 QQuiz5 questions
Which intermolecular force exists between every pair of molecules, even nonpolar ones?
ADipole-dipole forcesBHydrogen bondingCLondon dispersion forcesDIonic bonding
Chemistry · L3 · Intermolecular Forces — 5 Q
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Chemistry · L3 · Intermolecular Forces — 5 QQuiz6 questions
What is oxygen's oxidation number in hydrogen peroxide, H₂O₂?
A-2B-1C+1D+2
Chemistry · L3 · Oxidation States & Redox Balancing — 6 Q
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Chemistry · L3 · Oxidation States & Redox Balancing — 6 QQuiz6 questions
Ethene polymerizes into polyethylene by addition polymerization. What makes this possible?
AEthene has two reactive end groupsBEthene has a C=C double bond that opens up to link monomers togetherCEthene loses a water molecule at each linkDEthene is itself a natural polymer
Chemistry · L3 · Polymer Chemistry — 6 Q
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Chemistry · L3 · Polymer Chemistry — 6 QQuiz5 questions
A flame test on an unknown white powder produces a lilac flame. Which ion is most likely present?
ASodium, Na⁺BPotassium, K⁺CLithium, Li⁺DCalcium, Ca²⁺
Chemistry · L3 · Flame Tests & Ion Tests — 5 Q
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Chemistry · L3 · Flame Tests & Ion Tests — 5 QQuiz5 questions
Salt is spread on icy roads in winter. Which colligative property is being put to use?
AFreezing point depressionBBoiling point elevationCVapor pressure elevationDNone — this is a chemical reaction, not a colligative property
Chemistry · L3 · Colligative Properties — 5 Q
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Chemistry · L3 · Colligative Properties — 5 QQuiz6 questions
In electrolysis, cations migrate toward which electrode?
AThe cathodeBThe anodeCBoth electrodes equallyDNeither — they stay dispersed in the bulk liquid
Chemistry · L3 · Electrolysis — 6 Q
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Chemistry · L3 · Electrolysis — 6 QQuiz6 questions
What defines the limiting reagent in a chemical reaction?
AThe reactant present in the smallest massBThe reactant that runs out first, capping the amount of product that can formCThe reactant with the largest molar massDThe reactant listed first in the balanced equation
Chemistry · L3 · Limiting Reagents and Percent Yield — 6 Q
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Chemistry · L3 · Limiting Reagents and Percent Yield — 6 QQuiz5 questions
What does an empirical formula represent?
AThe exact number of atoms of each element in one moleculeBThe simplest whole-number ratio of atoms of each element in a compoundCThe total mass of the compound in gramsDThe number of moles in a 1 g sample
Chemistry · L3 · Empirical and Molecular Formula — 5 Q
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Chemistry · L3 · Empirical and Molecular Formula — 5 QQuiz5 questions
Why are pure metals malleable — able to be hammered or bent into new shapes without shattering?
ABecause metal atoms have no bonds holding them together at allBBecause layers of metal ions can slide past each other while the delocalised electron sea continuously re-bonds the new arrangementCBecause metals are always liquid at room temperatureDBecause metal ions repel each other and simply fall into a new position
Chemistry · L3 · Metallic Bonding and Why Alloys Are Harder — 5 Q
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Chemistry · L3 · Metallic Bonding and Why Alloys Are Harder — 5 Q