---
title: Olympiad: everyday chemistry detectives ★★★ — how Mova does on the tests · Chemistry
description: Lesson 37 of the chemistry course of Mova's primary school: 4 of 11 tests right, exam 1 of 4, every question with the options, the student's choice, the right answer and why it chose.
---

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# Olympiad: everyday chemistry detectives ★★★

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**Tests:** 4 of 11 right · **Exam:** 1 of 4 right · **Kind:** ★★★ · **Understood:** 10 of 15 · **Run:** 2026-10-18, commit `f3c23ea72`

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Lesson 37 of the chemistry course of Mova's primary school, as Mova's small model took its tests: it had read this lesson and the ones before it and learned from their exercises. Each test shows the options in the order the student saw them, its choice, the right answer, the score of every option and why it chose. The lesson itself, sentence by sentence with trees and pragmatics: [the lesson in the corpora](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/37-olympiad-everyday-chemistry-detectives/).

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Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: [the lesson's questions in the corpora](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/).

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### Test 1 · ★★★ · wrong ✗ {#t1}

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«me bike's a total pile of rust, can't even ride it» - you look and find three small orange spots on the chain guard. What's really going on?

- **1.** The orange is paint that rubbed off a gate — no support
- **2.** It has truly turned to rust from end to end — no support
- **3.** He's exaggerating: a few spots, best cleaned and painted — **✓ the right answer** · no support
- **4.** The bike is brand new and has no rust at all — **← Mova's choice** · score 8

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**Why:** It took the question to ask who or what does it. It chose option 4 with score 8, the only option with support. Its support: lesson 37, line 4: «People talk big and small: "my bike's a total pile of rust" may mean three orange spots, while "the kettle's got a bit of fur" may mean a crust as thick as a c…», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «bike» (+2); the same light verb (be, have, do, get, go) (+2). The right option, 3, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t1/)

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### Test 2 · ★★★ · right ✓ {#t2}

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«the kettle's got a bit of fur in it» says Dad. Inside there is a white crust as thick as a coin. What is true?

- **1.** He's playing it down: there's a lot of limescale — **← Mova's choice** · **✓ the right answer** · no support
- **2.** He's exaggerating: there's hardly any limescale in there — no support
- **3.** It is real fur shed by the cat — no support
- **4.** It is mould that grew in the hot water — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t2/)

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### Test 3 · ★★★ · wrong ✗ {#t3}

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Ruby reckons "rust gives you tetanus, so rusty stuff is poison." Which answer puts her right?

- **1.** She's right; the rust itself is the germ — **← Mova's choice** · score 6
- **2.** Rust is safe; only shiny metal causes it — score 6
- **3.** Tetanus floats in the air of rusty sheds — no support
- **4.** Tetanus is a germ in dirt; a deep cut from anything dirty can let it in — **✓ the right answer** · score 6

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**Why:** It took the question to ask who or what does it. It chose option 1 with score 6, tied with another option at 6 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 13, line 16: «Tetanus is caused by a germ in soil and dirt, not by rust; a deep cut from any dirty object can let it in, and vaccination protects you.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «germ» (+2). The right option, 4, scored 6. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t3/)

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### Test 4 · ★★★ · wrong ✗ {#t4}

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A Scottish gran says: «it's a dreich day, and look, me silver egg spoons have gone black. it's the rain, aye?» What is the better explanation?

- **1.** Aye, grey weather makes silver go dark — **← Mova's choice** · no support
- **2.** No, sulphur gas from the eggs tarnished them — **✓ the right answer** · no support
- **3.** No, the damp air is making the silver rust like iron — no support
- **4.** Aye, rain turns silver black overnight — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t4/)

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### Test 5 · ★★★ · wrong ✗ {#t5}

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A cartoon shows a cook throwing a bucket of water onto a burning chip pan, and the fire goes out at once. What is wrong?

- **1.** The water would freeze the oil solid at once — no support
- **2.** Nothing, but a bigger bucket would be better — no support
- **3.** Nothing, water puts out every kind of fire — **← Mova's choice** · score 1
- **4.** Water on burning oil throws it out in a fireball — **✓ the right answer** · no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 1, the only option with support. Its support: lesson 12, line 16: «Water puts out fires mainly by cooling, because it soaks up a lot of heat as it turns to steam.», reached through the option's own match among the sentences about the question's things. What matched: the same action «put out» (+1); the same doer «water» (+1). Against it: a different thing acted on (counts against) (-1). The right option, 4, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t5/)

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### Test 6 · ★★★ · right ✓ {#t6}

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«just chuck the dead batteries in the bin innit, they're empty anyway» What is the honest reply?

- **1.** Fine, as long as you put them in the bin when it rains — no support
- **2.** No, old batteries should go on the garden bonfire — no support
- **3.** No: they belong in collection boxes, as they can leak and start fires — **← Mova's choice** · **✓ the right answer** · score 6
- **4.** Fine, dead batteries have nothing left inside them — no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 6, the only option with support. Its support: lesson 32, line 11: «Batteries go in special collection boxes, never ordinary bins: they contain metals that harm nature if they leak and can be recovered, and batteries in bins ca…», reached through the remembered sentence the question matched. What matched: the same thing acted on «fires» (+3); the same action «start» (+2); the same doer «batteries» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t6/)

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### Test 7 · ★★★ · right ✓ {#t7}

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In Cape Town, Sipho says: "Squeeze a half-empty soda bottle before you close it and it stays fizzier, lekker trick!" Is he right?

- **1.** Yes, but it works only with diet drinks — no support
- **2.** Yes, the squeeze pushes the gas back into the drink — no support
- **3.** No, squeezing doesn't keep it fizzier — **← Mova's choice** · **✓ the right answer** · score 11
- **4.** No, the squeeze makes the bottle explode — no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 11, the only option with support. Its support: lesson 19, line 10: «An open drink goes flat as the gas slowly escapes; squeezing a half-empty plastic bottle before closing does not keep it fizzier.», reached through the same lesson line as the sentence the question matched. What matched: the same action «keep» (+4); the same doer «squeezing» (+4); the same thing acted on «bottle» (+2); the same property (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t7/)

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### Test 8 · ★★★ · wrong ✗ {#t8}

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«y'all, the tyre's flat as a pancake this frosty morning, it was fine yesterday arvo» The tyre looks only a little soft. What is the best detective guess?

- **1.** The cold air inside shrank, so the pressure dropped a bit — **✓ the right answer** · no support
- **2.** The air inside turned into water — no support
- **3.** The frost froze the rubber solid and it cracked — no support
- **4.** Tyres get much heavier in cold weather — **← Mova's choice** · score 5

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**Why:** It took the question to ask what it is done to. It chose option 4 with score 5, the only option with support. Its support: lesson 20, line 16: «Cold gas particles move slower and hit the walls less hard, so tyres have lower pressure in cold weather and drivers check them more often in winter.», reached through the option's own match among the sentences about the question's things. What matched: the same doer «tyres» (+3); the same place «cold weather» (+2). The right option, 1, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t8/)

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### Test 9 · ★★★ · wrong ✗ {#t9}

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«washing-up liquid in the dishwasher, what's the worst that could happen lol»

- **1.** The plates come out extra shiny and clean — **← Mova's choice** · no support
- **2.** The dishwasher freezes up with ice inside — no support
- **3.** Foam pours out all over the kitchen floor — **✓ the right answer** · no support
- **4.** Nothing at all, because soap is just soap — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t9/)

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### Test 10 · ★★★ · right ✓ {#t10}

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«this bubble bath must be cleaning me heaps, look at all the foam» What is true?

- **1.** Yes, but only the biggest bubbles clean — no support
- **2.** The soap cleans, foam or no foam — **← Mova's choice** · **✓ the right answer** · score 4
- **3.** No, bubbles leave you dirtier than before — no support
- **4.** Yes, more foam always means cleaner skin — no support

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**Why:** It took the question to ask which statement is true. It chose option 2 with score 4, the only option with support. Its support: lesson 37, line 14: «Soap and detergent do the cleaning, not the foam; washing-up liquid must never go in a dishwasher, because its foam would overflow.», reached through the remembered sentence the question matched. What matched: the same thing acted on «cleaning» (+3); the same doer «soap» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t10/)

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### Test 11 · ★★★ · wrong ✗ {#t11}

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A helium balloon from Saturday is small and wrinkly by Wednesday, with no hole. A little kid says it is "sad". What is really happening?

- **1.** The helium has slowly turned into air — no support
- **2.** The sunlight dried the balloon out — no support
- **3.** Helium slips out through the rubber — **✓ the right answer** · no support
- **4.** The balloon got heavier and sank in the cold — **← Mova's choice** · score 2

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**Why:** It took the question to ask which statement is true. It chose option 4 with score 2, the only option with support. Its support: lesson 4, line 10: «A blown-up balloon shrinks a little in the cold and grows again when warmed.», reached through the option's own match among the sentences about the question's things. What matched: the same place «cold» (+2); the same doer «blown balloon» (+1). Against it: a different action (counts against) (-1). The right option, 3, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/t11/)

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### Exam question 1 · formal language · right ✓ {#e1}

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Identify the conditions under which an iron nail will rust most rapidly.

- **1.** In salty water that is open to the air — **← Mova's choice** · **✓ the right answer** · score 3
- **2.** In a sealed jar of perfectly dry air — no support
- **3.** In boiled water beneath a layer of oil — no support
- **4.** In a vacuum with no water present — no support

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 3, the only option with support. Its support: lesson 1, line 18: «Your body is built from the atoms in the food you eat, the water you drink and the air you breathe.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «food» (+2); the same circumstance (+2). Against it: a different doer (counts against) (-1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/e1/)

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### Exam question 2 · formal language · wrong ✗ {#e2}

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Determine which of the following objects would be attracted by a magnet.

- **1.** A pure gold coin — **← Mova's choice** · no support
- **2.** A length of copper wire — no support
- **3.** An aluminium drinks can — no support
- **4.** A steel paperclip — **✓ the right answer** · no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/e2/)

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### Exam question 3 · formal language · wrong ✗ {#e3}

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A candle placed beneath an inverted jar is extinguished. Ascertain the reason.

- **1.** The jar has cooled the wax so that it cannot melt — no support
- **2.** The wick has been dissolved by water vapour — **← Mova's choice** · score 8
- **3.** The oxygen within the jar has largely been used up — **✓ the right answer** · no support
- **4.** The carbon dioxide inside has caught fire — score 6

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**Why:** It took the question to ask which statement is true. It chose option 2 with score 8, against 6 for the next best. Its support: lesson 15, line 17: «Gases from factory and car smoke dissolve in raindrops and make acid rain, which damaged forests and stone buildings; cleaner factories have reduced it a lot.», reached through the same lesson line as the sentence the question matched. What matched: the same action «dissolve» (+4); the same doer «gases» (+4). The right option, 3, found no support in what it remembers. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/e3/)

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### Exam question 4 · formal language · wrong ✗ {#e4}

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State which ordering of waste practices is recommended.

- **1.** Landfill, then recycle, then reduce — **← Mova's choice** · no support
- **2.** Reduce, then reuse, then recycle — **✓ the right answer** · no support
- **3.** Recycle, then reduce, then reuse — no support
- **4.** Reuse, then recycle, then reduce — no support

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**Why:** No option found support in what it remembers, so it guessed: it took the first option shown. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/37-olympiad-everyday-chemistry-detectives/e4/)

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- ← previous: [36. Olympiad: kitchen chemistry puzzles ★★★](https://md.mova.elamur.ai/free/en/school-run/chemistry/36-olympiad-kitchen-chemistry-puzzles/)
- ↑ back to [Chemistry](https://md.mova.elamur.ai/free/en/school-run/chemistry/)