---
title: Floating in the real world: ice, submarines and balloons — how Mova does on the tests · Physics
description: Lesson 12 of the physics course of Mova's primary school: 7 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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# Floating in the real world: ice, submarines and balloons

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**Tests:** 7 of 11 right · **Exam:** 1 of 4 right · **Kind:** ★ · **Understood:** 11 of 15 · **Run:** 2026-10-18, commit `f3c23ea72`

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Lesson 12 of the physics 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/physics/12-ice-submarines-and-balloons/).

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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/physics/12-ice-submarines-and-balloons/).

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### Test 1 · ★ · right ✓ {#t1}

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bro just let the balloons go at the party, they'll come back right

- **1.** No, they float in space for ever — score 4
- **2.** Yes, balloons always float back down — no support
- **3.** No, they rise until they pop and can harm wildlife — **← Mova's choice** · **✓ the right answer** · score 7
- **4.** Yes, the wind brings them home — no support

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**Why:** It took the question to ask which statement is true. It chose option 3 with score 7, against 4 for the next best. Its support: lesson 12, line 10: «Helium is much lighter than air, so the air pushes a helium balloon up; let go outside, it rises until it pops, and balloons can harm wildlife.», reached through the remembered sentence the question matched. What matched: the same action «harm» (+3); the same thing acted on «wildlife» (+3); the same doer «balloons» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t1/)

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### Test 2 · ★ · right ✓ {#t2}

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What would happen to a pond in winter if ice sank?

- **1.** Fish would float on the ice — no support
- **2.** It would freeze from the bottom up — **← Mova's choice** · **✓ the right answer** · score 8
- **3.** It would never freeze at all, however cold it got — no support
- **4.** It would turn into oil — no support

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**Why:** It took the question to ask what happens next. It chose option 2 with score 8, the only option with support. Its support: lesson 12, line 6: «If ice sank, ponds would freeze from the bottom up and fish could not survive the winter.», reached through what followed the sentence the question matched. What matched: the same action «freeze up» (+5); the same place «bottom» (+4). 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/physics/12-ice-submarines-and-balloons/t2/)

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### Test 3 · ★ · wrong ✗ {#t3}

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In a film a whole ship hits a tiny bit of ice and sinks. Why is that not so strange?

- **1.** Only the tip of a ship is strong — **← Mova's choice** · no support
- **2.** Ice is heavier than steel — no support
- **3.** The ice pulled the ship down with its icy weight — no support
- **4.** Most of the iceberg was hidden under water — **✓ 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/physics/12-ice-submarines-and-balloons/t3/)

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### Test 4 · ★ · right ✓ {#t4}

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Mia says oil sinks cos it's thick and heavy. right?

- **1.** Yes, thick and heavy liquids always sink to the bottom — no support
- **2.** No, oil floats because it is lighter for its size — **← Mova's choice** · **✓ the right answer** · score 8
- **3.** No, oil floats because it is hot — no support
- **4.** Yes, oil sinks in the sea — score 3

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**Why:** It took the question to ask which statement is true. It chose option 2 with score 8, against 3 for the next best. Its support: lesson 12, line 12: «Oil is lighter than water for its size and does not mix with it, so spilled oil spreads over the sea and coats birds' feathers.», reached through the remembered sentence the question matched. What matched: the same circumstance (+5); the same light verb (be, have, do, get, go) (+2); the same doer «oil» (+1). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t4/)

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### Test 5 · ★ · wrong ✗ {#t5}

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You put a can of normal cola and a can of diet cola in a bowl of water. What happens?

- **1.** Both float on the top, because the cans are full of air — **← Mova's choice** · score 4
- **2.** The normal one floats — score 4
- **3.** Both sink to the bottom — no support
- **4.** The diet one floats and the normal one sinks — **✓ the right answer** · score 4

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**Why:** It took the question to ask what happens next. It chose option 1 with score 4, tied with another option at 4 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 12, line 13: «A can of normal cola sinks and a can of diet cola floats, because the sugar in normal cola makes it a little heavier.», reached through what followed the sentence the question matched. What matched: the same action «float» (+5). Against it: a different doer (counts against) (-1). The right option, 4, scored 4. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t5/)

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### Test 6 · ★ · wrong ✗ {#t6}

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What would a submarine do if it could not blow its tanks?

- **1.** It could not come back up — **✓ the right answer** · no support
- **2.** It would rise faster — **← Mova's choice** · score 7
- **3.** It would float on its side — no support
- **4.** It would turn into a boat — no support

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**Why:** It took the question to ask what is done. It chose option 2 with score 7, the only option with support. Its support: lesson 12, line 8: «A submarine fills tanks with seawater to sink and blows them out with air to rise.», reached through a sentence linked to the one the question matched. What matched: it fills the role the question asks for (+3); the same action «rise» (+2); the same doer «submarine» (+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/physics/12-ice-submarines-and-balloons/t6/)

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### Test 7 · ★ · wrong ✗ {#t7}

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Why is a helium balloon like a piece of wood in a pond?

- **1.** Both are lighter than what surrounds them, so they rise — **✓ the right answer** · no support
- **2.** Both sink slowly — score 2
- **3.** Both are heavier than air — **← Mova's choice** · score 6
- **4.** Both are made of plant stuff — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 3 with score 6, against 2 for the next best. Its support: lesson 12, line 3: «Air pushes up just like water, only more gently, so a helium balloon or a hot-air balloon floats in the air like wood floats in a pond.», reached through the cause of the sentence the question matched. What matched: the same circumstance (+6). 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/physics/12-ice-submarines-and-balloons/t7/)

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### Test 8 · ★ · right ✓ {#t8}

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You push a resting paper clip through the water's skin. What happens?

- **1.** It stays hanging halfway down the glass — score 4
- **2.** It jumps right out of the water again — score 2
- **3.** It floats back up to the surface — score 2
- **4.** It sinks straight to the bottom — **← Mova's choice** · **✓ the right answer** · score 9

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**Why:** It took the question to ask what happens next. It chose option 4 with score 9, against 4 for the next best. Its support: lesson 12, line 16: «A steel paper clip placed gently rests on the water's skin; it is not floating like a boat, and pushed through the skin it sinks.», reached through what followed the sentence the question matched. What matched: the same action «sink» (+5); the same doer «clip» (+4). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t8/)

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### Test 9 · ★ · right ✓ {#t9}

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People crossing a river on a bottle raft should also...

- **1.** Open all the bottles — no support
- **2.** Fill the bottles with water — no support
- **3.** Sit on the edge — no support
- **4.** Wear life jackets — **← Mova's choice** · **✓ the right answer** · score 4

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**Why:** It took the question to ask which statement is true. It chose option 4 with score 4, the only option with support. Its support: lesson 12, line 17: «Sealed plastic bottles are full of air, so a raft of many bottles can hold up a child, but people on such rafts should still wear life jackets.», reached through the option's own match among the sentences about the question's things. What matched: the same action «wear» (+2); the same thing acted on «life jackets» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t9/)

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### Test 10 · ★ · right ✓ {#t10}

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A hot-air balloon pilot stops firing the burner. What happens?

- **1.** The balloon pops with a big bang — no support
- **2.** The balloon slowly sinks — **← Mova's choice** · **✓ the right answer** · score 2
- **3.** The balloon shoots straight up — no support
- **4.** Nothing at all changes up there — no support

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**Why:** It took the question to ask what happens next. It chose option 2 with score 2, the only option with support. Its support: lesson 12, line 11: «Hot air spreads out and gets lighter for its size than the cold air around it, so a hot-air balloon rises, and sinks slowly as the air inside cools, so the pil…», reached through the same lesson line as the sentence the question matched. What matched: the same action «sink» (+2); the same property (+1). 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/physics/12-ice-submarines-and-balloons/t10/)

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### Test 11 · ★ · right ✓ {#t11}

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Which shows that water grows bigger when it freezes?

- **1.** Rain falls from clouds — no support
- **2.** Ice cubes melt quickly when you drop them in a warm drink — no support
- **3.** A full bottle left in the freezer can crack — **← Mova's choice** · **✓ the right answer** · score 7
- **4.** Snow is white and soft — no support

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**Why:** It took the question to ask who or what does it. It chose option 3 with score 7, the only option with support. Its support: lesson 12, line 5: «Water grows bigger when it freezes, because its molecules line up in an open pattern with gaps, so ice floats, and a full bottle of water left in the freezer c…», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+3); the same action «crack» (+2); the same doer «full bottle» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/t11/)

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

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Which of the following statements most accurately characterises the reason for which ice floats upon water?

- **1.** Water expands upon freezing, so that ice is of lesser density — **← Mova's choice** · **✓ the right answer** · score 10
- **2.** Cold bodies are invariably repelled by water — score 5
- **3.** Ice contains a large quantity of trapped helium — score 8
- **4.** Ice is supported by the walls of its container — no support

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**Why:** It took the question to ask who or what does it. It chose option 1 with score 10, against 8 for the next best. Its support: lesson 12, line 2: «Water is strange: it grows bigger when it freezes, so ice is lighter for its size than water and floats, which saves fish in frozen ponds.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same doer «ice» (+4). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/physics/12-ice-submarines-and-balloons/e1/)

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

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Identify the principal means by which a submarine is caused to descend.

- **1.** The folding of external wings — **← Mova's choice** · no support
- **2.** The extinguishing of its interior lights — no support
- **3.** The release of all the air through its hatches into the sea — no support
- **4.** The admission of seawater into its ballast tanks — **✓ 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/physics/12-ice-submarines-and-balloons/e2/)

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

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It is given that the air within a hot-air balloon is permitted to cool. Ascertain the consequence for the balloon.

- **1.** It bursts immediately — **← Mova's choice** · no support
- **2.** It descends gradually — **✓ the right answer** · no support
- **3.** It ascends rapidly — no support
- **4.** It remains at a fixed altitude — 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/physics/12-ice-submarines-and-balloons/e3/)

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

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Determine the reason for which a steel paper clip, gently placed, remains upon the surface of water.

- **1.** It is attracted upwards by the air — **← Mova's choice** · no support
- **2.** It is supported by the surface layer of the water — **✓ the right answer** · no support
- **3.** It is of lesser density than water — no support
- **4.** It is buoyed up by the hollow interior of the steel wire — 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/physics/12-ice-submarines-and-balloons/e4/)

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- ← previous: [11. Floating and sinking: the push of the water](https://md.mova.elamur.ai/free/en/school-run/physics/11-floating-and-sinking/)
- next →: [13. Water safety and the ocean](https://md.mova.elamur.ai/free/en/school-run/physics/13-water-safety-and-the-ocean/)
- ↑ back to [Physics](https://md.mova.elamur.ai/free/en/school-run/physics/)