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OpenStem
@openstem · Joined Jul 2026
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Quiz5 questions
What happens to chocolate when it gets hot?
AIt melts into a liquidBIt turns to steamCIt gets harderDIt disappears completely
Chemistry · L1 · Heating and Cooling in the Kitchen
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Chemistry · L1 · Heating and Cooling in the KitchenQuiz5 questions
What happens when you make a fruit salad?
AThe fruits melt together into one new fruitBYou mix different fruits together, but each stays itselfCThe fruits turn into juiceDYou cook the fruits until they disappear
Chemistry · L1 · Mixing in the Kitchen Quiz
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Chemistry · L1 · Mixing in the Kitchen QuizQuiz5 questions
What happens to ice in a glass of water?
AIt sinks to the bottomBIt floats on topCIt disappears instantlyDIt turns the water red
Chemistry · L1 · Water, a Special Liquid
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Chemistry · L1 · Water, a Special LiquidQuiz5 questions
Which of these is a natural material?
APlasticBNylonCWoolDPolyester
Chemistry · L1 · Natural and Human-made Materials
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Chemistry · L1 · Natural and Human-made MaterialsQuiz5 questions
What should you do if you find a bottle you don't recognize?
ATaste it to find out what it isBSmell it closelyCAsk a grown-upDPour it down the sink yourself
Chemistry · L1 · Staying Safe with Chemicals
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Chemistry · L1 · Staying Safe with ChemicalsQuiz5 questions
Why do we sort rubbish into different bins?
ATo make more rubbishBSo each material can be recycled properlyCBecause it looks tidyDAll bins are the same anyway
Chemistry · L1 · Sorting and Recycling Materials
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Chemistry · L1 · Sorting and Recycling MaterialsQuiz5 questions
What colour does a rusty nail turn?
ABright blueBOrange-brownCPurpleDBlack
Chemistry · L1 · Colours That Change
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Chemistry · L1 · Colours That ChangeQuiz6 questions
Why can't we usually see the air around us?
ABecause it is not really thereBBecause air is invisible, even though it is realCBecause air only appears at nightDBecause air is a solid
Chemistry · L1 · Air, Breathing, and Gases
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Chemistry · L1 · Air, Breathing, and GasesQuiz6 questions
What makes the bubbles in a fizzy drink?
ACarbon dioxide gas that was dissolved in the liquidBTiny pieces of sugar floating upCAir leaking in through the capDThe liquid boiling
Chemistry · L1 · Fizzy Drinks and Dissolved Gas
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Chemistry · L1 · Fizzy Drinks and Dissolved GasQuiz5 questions
What is left behind when salty water evaporates?
ASolid salt crystalsBNothing at allCMore waterDA cloud of gas
Chemistry · L1 · Growing Crystals at Home
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Chemistry · L1 · Growing Crystals at HomeQuiz6 questions
What makes bread dough puff up?
ATiny trapped bubbles of gasBThe dough getting colderCExtra water soaking inDThe dough turning into a solid rock
Chemistry · L1 · Why Bread and Cakes Rise
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Chemistry · L1 · Why Bread and Cakes RiseQuiz5 questions
Why doesn't plain water wash grease off a pan?
AThe water is too coldBGrease and water do not mixCGrease is too heavy for waterDThe water evaporates too fast
Chemistry · L1 · How Soap Cleans
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Chemistry · L1 · How Soap CleansQuiz6 questions
Which of these sticks to a magnet?
AAluminium foilBCopper wireCIron nailDGold ring
Chemistry · L1 · Testing with Magnets
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Chemistry · L1 · Testing with MagnetsQuiz6 questions
What is a smell actually made of?
ANothing — smells are just imaginedBTiny, invisible particles floating in the airCA special kind of lightDSound waves
Chemistry · L1 · Where Do Smells Come From?
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Chemistry · L1 · Where Do Smells Come From?Quiz5 questions
Why is one H2 molecule released as an obligate byproduct of nitrogenase turnover?
AIt is a mechanistic consequence of the enzyme's electron/proton delivery cycle, built into the reaction stoichiometry regardless of catalyst efficiencyBIt only occurs when the enzyme is inhibited by excess oxygenCIt is a side reaction that can be eliminated by protein engineering without affecting N2 reductionDIt results from adventitious water contamination in the assay
Chemistry · L5 · Bioinorganic Metalloenzymes
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Chemistry · L5 · Bioinorganic MetalloenzymesQuiz6 questions
Two identical bikes are left out for a month — one in the rain, one in a dry shed. Which one is more likely to rust?
AThe one in the dry shedBThe one left out in the rainCNeither will rustDBoth will rust the same amount
Chemistry · L1 · Weathering: Why Outdoor Metal Rusts
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Chemistry · L1 · Weathering: Why Outdoor Metal RustsQuiz5 questions
Why do people spread salt on icy roads and sidewalks in winter?
ATo make the ice taste betterBTo make it much harder for the water to stay frozen, turning ice into safer slushCTo make the ice look prettierDTo make the ice freeze even harder
Chemistry · L1 · Why Salt Melts Icy Roads
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Chemistry · L1 · Why Salt Melts Icy RoadsQuiz6 questions
What can you use to write a lemon juice secret message?
AA paintbrush with paintBA cotton swab or toothpick dipped in lemon juiceCA pencilDA marker
Chemistry · L1 · Secret Messages with Invisible Ink
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Chemistry · L1 · Secret Messages with Invisible InkQuiz6 questions
What happens when you drop food colouring into still water and don't stir it?
AIt sinks straight to the bottom and stays thereBIt slowly spreads into tendrils until the water is evenly colouredCIt disappears completelyDNothing happens at all
Chemistry · L1 · Why Food Colouring Spreads Through Water
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Chemistry · L1 · Why Food Colouring Spreads Through WaterQuiz6 questions
Why does a helium-filled balloon float up through the air?
ABecause balloons are always lighter than air, no matter what is insideBBecause the helium inside is packed together more loosely than the air around itCBecause helium is a bright colorDBecause the string pulls it upward
Chemistry · L1 · Why Helium Balloons Float Up
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Chemistry · L1 · Why Helium Balloons Float UpQuiz5 questions
How does an acid like lemon juice usually taste?
ASourBBitter and soapyCSweetDSalty
Chemistry · L1 · Sour or Soapy? Acids and Bases in the Kitchen
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Chemistry · L1 · Sour or Soapy? Acids and Bases in the KitchenQuiz5 questions
What are the three things every flame needs to keep burning?
AFuel, oxygen, and heatBWater, salt, and sugarCWax, string, and lightDCold air, wax, and water
Chemistry · L1 · Why a Candle Burns
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Chemistry · L1 · Why a Candle BurnsQuiz5 questions
What does melting always need to happen?
AHeatBA liquid to spread intoCStirringDSalt
Chemistry · L1 · Dissolving vs. Melting
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Chemistry · L1 · Dissolving vs. MeltingQuiz5 questions
What happens to a puddle on a hot, sunny day?
AIt freezesBIt evaporates into invisible water vaporCIt turns into a new substanceDNothing happens to it
Chemistry · L1 · Evaporation and Condensation
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Chemistry · L1 · Evaporation and CondensationQuiz5 questions
Why do people sprinkle salt on icy sidewalks?
ASalt makes the ice colder instantlyBSalt lowers the temperature the ice needs to refreeze at, so it melts and stays meltedCSalt turns the ice into a new substanceDSalt has nothing to do with the ice
Chemistry · L1 · Why Salt Melts Sidewalk Ice Faster
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Chemistry · L1 · Why Salt Melts Sidewalk Ice FasterQuiz5 questions
What happens when you add vinegar to milk?
ANothing changesBThe milk curdles into curds and wheyCThe milk turns into waterDThe milk freezes
Chemistry · L1 · Milk and Vinegar Curdling
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Chemistry · L1 · Milk and Vinegar CurdlingQuiz5 questions
What is a mixture?
AA brand new substance made from heating thingsBTwo or more things stirred together without becoming something newCOnly something you can see throughDA liquid only
Chemistry · L1 · Mixtures vs. Solutions
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Chemistry · L1 · Mixtures vs. SolutionsQuiz5 questions
What happens when you pour oil and water into the same jar and let it sit?
AThey mix into one liquid foreverBThey separate into two layersCThe water disappearsDThe oil sinks to the bottom
Chemistry · L1 · Oil and Water Don't Mix
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Chemistry · L1 · Oil and Water Don't MixQuiz5 questions
Is a black marker always made of just one plain color?
AYes, alwaysBNo, it is often a mix of several hidden colorsCOnly if it is a new markerDOnly if it is a permanent marker
Chemistry · L1 · Hidden Colors in a Black Marker
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Chemistry · L1 · Hidden Colors in a Black MarkerQuiz5 questions
Which state of matter always keeps its own shape?
AGasBLiquidCSolidDNone of them
Chemistry · L1 · Solid, Liquid, or Gas?
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Chemistry · L1 · Solid, Liquid, or Gas?