---
title: Melting, freezing, boiling and condensing — how Mova does on the tests · Chemistry
description: Lesson 5 of the chemistry course of Mova's primary school: 4 of 10 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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# Melting, freezing, boiling and condensing

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**Tests:** 4 of 10 right · **Exam:** 1 of 4 right · **Kind:** ★ · **Understood:** 6 of 14 · **Run:** 2026-10-18, commit `f3c23ea72`

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Lesson 5 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/5-melting-freezing-boiling-condensing/).

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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/5-melting-freezing-boiling-condensing/).

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### Test 1 · ★ · wrong ✗ {#t1}

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Your friend says: "That can of cola is leaking, look, it's all wet outside." How could you show the water came from the air?

- **1.** Weigh the can every hour and see that it is slowly getting lighter — **← Mova's choice** · no support
- **2.** Shake the can to see if it leaks more — no support
- **3.** Taste the water to see if it is cola — no support
- **4.** Put a cold empty can or glass out and it gets wet too — **✓ 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/5-melting-freezing-boiling-condensing/t1/)

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### Test 2 · ★ · wrong ✗ {#t2}

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

- **1.** It could freeze from the bottom up, and fish would be in danger — **✓ the right answer** · no support
- **2.** Nothing, ponds never freeze — score 2
- **3.** The ice would melt at once — **← Mova's choice** · score 4
- **4.** Fish would be much warmer in winter, under a thick blanket of ice — no support

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**Why:** It took the question to ask what happens next. It chose option 3 with score 4, against 2 for the next best. Its support: lesson 5, line 6: «Ice melts at 0 °C; chocolate melts at about 34 °C, just below the temperature inside your mouth.», reached through the option's own match among the sentences about the question's things. What matched: the same action «melt» (+2); the same doer «ice» (+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/5-melting-freezing-boiling-condensing/t2/)

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### Test 3 · ★ · wrong ✗ {#t3}

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"it's minus 25 out, why aren't they salting the roads, lazy council" What is a better reason?

- **1.** Roads cannot get icy below minus 20 — **← Mova's choice** · no support
- **2.** Salt does not melt ice well in such hard frost — **✓ the right answer** · no support
- **3.** Salt only works on roads in the summer months — no support
- **4.** Salt makes ice thicker at minus 25 — no support

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**Why:** Nothing it remembers matched the question, 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/5-melting-freezing-boiling-condensing/t3/)

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### Test 4 · ★ · right ✓ {#t4}

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A cartoon shows someone picking up dry ice with bare hands to make "party smoke". What is wrong?

- **1.** Dry ice burns skin with cold and must never be touched bare — **← Mova's choice** · **✓ the right answer** · score 6
- **2.** Dry ice is hot and burns like fire — no support
- **3.** Dry ice melts into water on hands — score 4
- **4.** Nothing, dry ice is just as safe to hold as the ice cubes from the freezer — no support

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 6, against 4 for the next best. Its support: lesson 5, line 15: «Dry ice is frozen carbon dioxide that turns straight into gas; it must never be touched with bare hands, because it burns with cold.», reached through the remembered sentence the question matched. What matched: the same action «touch» (+4); the same property (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/5-melting-freezing-boiling-condensing/t4/)

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### Test 5 · ★ · right ✓ {#t5}

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Your little brother says: "Puddles go away because the ground drinks them all." Put him right.

- **1.** Much of the water evaporates into the air — **← Mova's choice** · **✓ the right answer** · no support
- **2.** He is right, the air takes none of it at all — no support
- **3.** The water turns into mud forever — no support
- **4.** Clouds suck puddles up through straws — 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/5-melting-freezing-boiling-condensing/t5/)

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### Test 6 · ★ · wrong ✗ {#t6}

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"why'm I freezing getting out the pool when it's windy, bloody hell" Best answer?

- **1.** Wind blows the cold pool water back all over you, again and again — **← Mova's choice** · no support
- **2.** The wind is always colder than the water — no support
- **3.** Your skin stops working in wind — no support
- **4.** The wind speeds up evaporation, which takes heat from you — **✓ 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/5-melting-freezing-boiling-condensing/t6/)

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### Test 7 · ★ · right ✓ {#t7}

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Why can you see your breath in winter but not in summer?

- **1.** You breathe out much less air in summer — no support
- **2.** Summer sunlight hides your breath — no support
- **3.** In warm air the vapour stays an invisible gas — **← Mova's choice** · **✓ the right answer** · score 2
- **4.** Summer breath has no water in it — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 3 with score 2, the only option with support. Its support: lesson 5, line 10: «You see your breath on a frosty morning because the warm vapour in it condenses into tiny droplets in the cold air.», reached through the cause of the sentence the question matched. What matched: the same doer «warm vapour» (+4). Against it: a different action (counts against) (-2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/5-melting-freezing-boiling-condensing/t7/)

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### Test 8 · ★ · wrong ✗ {#t8}

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Your cousin says: "Boiling means the water is 100 degrees, so it's the same on every mountain." Put him right.

- **1.** Water boils hotter on mountains — **← Mova's choice** · score 8
- **2.** He is right, it is always 100 degrees everywhere — no support
- **3.** Water can't boil above the clouds — score 2
- **4.** Water boils at a lower temperature high up — **✓ the right answer** · score 8

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 8, tied with another option at 8 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 5, line 11: «At sea level water boils at 100 °C; high on a mountain it boils at a lower temperature, so pasta takes longer to cook.», reached through the remembered sentence the question matched. What matched: the same action «boil» (+4); the same doer «water» (+4). The right option, 4, scored 8. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/5-melting-freezing-boiling-condensing/t8/)

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### Test 9 · ★ · wrong ✗ {#t9}

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A bag of ice and salt feels too cold to hold. Why?

- **1.** The salt in the bag is frozen solid, and frozen salt is the coldest thing there is — **← Mova's choice** · no support
- **2.** The bag is made of cold plastic — no support
- **3.** Salt bites the skin like a crab — no support
- **4.** The salted ice melts and draws heat from everything around, your hands too — **✓ 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/5-melting-freezing-boiling-condensing/t9/)

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### Test 10 · ★ · right ✓ {#t10}

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Why do frozen water pipes sometimes burst in winter?

- **1.** Water expands as it freezes and pushes the pipe apart — **← Mova's choice** · **✓ the right answer** · score 4
- **2.** Frozen water gets heavier and drops — no support
- **3.** Cold metal turns to powder — no support
- **4.** Ice is very sharp and cuts the pipe open from inside — no support

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**Why:** It took the question to ask why something happens (its cause). It chose option 1 with score 4, the only option with support. Its support: lesson 5, line 13: «Water expands when it freezes, so ice floats, ponds freeze from the top down and frozen pipes can burst.», reached through the same lesson line as the sentence the question matched. What matched: the same action «expand» (+2); the same doer «water» (+2). · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/5-melting-freezing-boiling-condensing/t10/)

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### Exam question 1 · formal language · wrong ✗ {#e1}

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Which of the following statements most accurately characterises condensation?

- **1.** The conversion of a liquid into a solid by cooling — **← Mova's choice** · no support
- **2.** The conversion of a vapour into a liquid upon contact with a cooler surface — **✓ the right answer** · no support
- **3.** The conversion of a solid into a liquid by the application of heat from without — no support
- **4.** The conversion of a liquid into a vapour at its surface — no support

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**Why:** Nothing it remembers matched the question, 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/5-melting-freezing-boiling-condensing/e1/)

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

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It is given that a sealed vessel completely filled with water has been placed in a freezer and is subsequently found fractured. Identify the principal cause.

- **1.** The vessel was attacked by the freezer's cold air — **← Mova's choice** · no support
- **2.** The water contracted upon freezing and drew the walls inward — no support
- **3.** The ice acquired a greater mass than the water — no support
- **4.** The water expanded in volume upon freezing — **✓ 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/5-melting-freezing-boiling-condensing/e2/)

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### Exam question 3 · formal language · right ✓ {#e3}

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Select the response that is consistent with the established facts concerning the boiling of water at high altitude.

- **1.** Water boils at a temperature lower than 100 °C — **← Mova's choice** · **✓ the right answer** · no support
- **2.** Water boils at a temperature higher than 100 °C — no support
- **3.** Water cannot be brought to the boil — no support
- **4.** Water boils at exactly 100 °C invariably — no support

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**Why:** Nothing it remembers matched the question, 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/5-melting-freezing-boiling-condensing/e3/)

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

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Identify the principal reason for which evaporation of water from the skin produces a sensation of cold.

- **1.** Water is invariably colder than the skin — **← Mova's choice** · score 8
- **2.** The escaping particles carry heat away from the body — **✓ the right answer** · score 4
- **3.** Evaporation introduces cold air into the skin — no support
- **4.** The skin produces cold in response to moisture — no support

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**Why:** It took the question to ask which statement is true. It chose option 1 with score 8, against 4 for the next best. Its support: lesson 5, line 17: «Water evaporating from your skin takes heat away, which is why sweat cools you and wet hair feels cold.», reached through the remembered sentence the question matched. What matched: the same doer «water» (+4); the same circumstance (+4). The right option, 2, scored 4. · [the question and its options parsed, with trees and pragmatics](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/5-melting-freezing-boiling-condensing/e4/)

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- ← previous: [4. Solids, liquids and gases](https://md.mova.elamur.ai/free/en/school-run/chemistry/4-solids-liquids-and-gases/)
- next →: [6. Mixing and dissolving](https://md.mova.elamur.ai/free/en/school-run/chemistry/6-mixing-and-dissolving/)
- ↑ back to [Chemistry](https://md.mova.elamur.ai/free/en/school-run/chemistry/)