Gases all around: breath and balloons

Tests: 6 of 11 right · Exam: 3 of 4 right · Kind: ★ · Understood: 11 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 20 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.

Every question of this lesson and each of its options parsed by Mova, with trees and pragmatics: the lesson's questions in the corpora.

Test 1 · ★ · right ✓

"i breathed on the window and drew a smiley in it. where'd the wet come from??"

1. Water vapour in your breath — ← Mova's choice · ✓ the right answer · no support
2. Spit from your mouth only — no support
3. The glass made it — no support
4. Rain on the other side — no support

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

Test 2 · ★ · wrong ✗

Ellie says helium balloons go down because the helium "gets tired". What's true?

1. The balloon fills up with water — ← Mova's choice · no support
2. Air pushes the helium out through the knot — no support
3. Helium loses all its lift after a day — no support
4. Tiny helium atoms escape through the rubber — ✓ the right answer · no support

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

Test 3 · ★ · right ✓

The party planner wants to release 100 balloons into the sky. What's the problem?

1. Nothing, balloons vanish in the sky — no support
2. They come down and can harm animals — ← Mova's choice · ✓ the right answer · score 17
3. They will burst the clouds — no support
4. They will block aeroplanes — no support

Why: It took the question to ask what it is done to. It chose option 2 with score 17, the only option with support. Its support: lesson 20, line 8: «Released balloons come down far away, do not break down quickly and can harm animals that eat them; many places now ban balloon releases.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «animals» (+5); the same action «harm» (+4); the same doer «released balloons» (+2). · the question and its options parsed, with trees and pragmatics

Test 4 · ★ · right ✓

If the burner of a hot-air balloon stopped working high in the sky, what would happen?

1. The air inside would cool and the balloon would sink — ← Mova's choice · ✓ the right answer · no support
2. The balloon would stay still for ever — no support
3. The balloon would shoot up faster — no support
4. The balloon would burst at once — no support

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

Test 5 · ★ · wrong ✗

"dad's gonna fix the car in the garage with the engine running and the door shut". What's the danger?

1. The garage will get far too cold to work in — no support
2. Carbon monoxide builds up, with no smell — ✓ the right answer · no support
3. Nothing, exhaust is just steam — no support
4. The car will run out of petrol — ← Mova's choice · score 1

Why: It took the question to ask what it is done to. It chose option 4 with score 1, the only option with support. Its support: lesson 20, line 13: «Carbon monoxide has no smell and can kill, so a car must never run in a closed garage and carbon monoxide alarms are useful at home.», reached through the option's own match among the sentences about the question's things. What matched: the same action «run» (+2); the same doer «car» (+2). Against it: one says «not», the other does not (counts against) (-3). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 6 · ★ · right ✓

In class, Sam pumps air into lime water and nothing much happens; then he breathes into it and it goes milky. Why the difference?

1. Breath is warmer, and lime water likes heat — score 2
2. The pump was broken — no support
3. Sam's breath had sweets in it — no support
4. Breath has much more carbon dioxide — ← Mova's choice · ✓ the right answer · score 4

Why: It took the question to ask which statement is true. It chose option 4 with score 4, against 2 for the next best. Its support: lesson 20, line 6: «Breath has much more carbon dioxide than ordinary air; carbon dioxide turns lime water milky by making tiny chalk particles, a test scientists use.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «more carbon dioxide» (+2); the same doer «breath» (+1); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Test 7 · ★ · right ✓

"the hot spring stinks of rotten eggs, did someone drop eggs in it?"

1. Yes, birds lay eggs in the spring — score 6
2. No, it gives off the same gas, hydrogen sulphide — ← Mova's choice · ✓ the right answer · score 8
3. Yes, people throw eggs in for luck every single day — no support
4. No, it is the smell of hot water — no support

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 14, line 6: «Eggs, onions and some rubber give off sulphur gases, so silver egg spoons tarnish very quickly.», reached through the remembered sentence the question matched. What matched: the same action «give off» (+4); the same thing acted on «sulphur gases» (+4). · the question and its options parsed, with trees and pragmatics

Test 8 · ★ · right ✓

In a cartoon, a balloon is filled with hot air and then left in a freezer, where it floats up. What would really happen?

1. The air would cool and the balloon would shrink and sink — ← Mova's choice · ✓ the right answer · score 2
2. It would turn into ice and fly — score 2
3. It would burst from the cold — score 2
4. It would float higher in the cold — score 2

Why: It took the question to ask which statement is true. It chose option 1 with score 2, tied with another option at 2 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 11, line 10: «The water that rises in a jar over a candle in water is not only because oxygen is used up; the air in the jar also cools and shrinks.», reached through the option's own match among the sentences about the question's things. What matched: the same action «cool» (+1); the same doer «air» (+1). · the question and its options parsed, with trees and pragmatics

Test 9 · ★ · wrong ✗

Pondweed in a jar on the windowsill makes bubbles all day. What happens at night?

1. The jar fills with water vapour — no support
2. The bubbles get faster — no support
3. The bubbles stop — ✓ the right answer · no support
4. The bubbles turn red — ← Mova's choice · score 5

Why: It took the question to ask which statement is true. It chose option 4 with score 5, the only option with support. Its support: lesson 19, line 6: «Shaking a bottle makes many tiny bubbles that grow quickly when it is opened, so it sprays.», reached through the same lesson line as the sentence the question matched. What matched: the same action «grow» (+3); the same doer «many tiny bubbles» (+2). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 10 · ★ · wrong ✗

"tyre was fine yesterday, looks flat this morning, it's minus 5". What's the likely reason?

1. Frost has leaked into it — no support
2. Cold air in it pushes less on the walls — ✓ the right answer · no support
3. A hedgehog bit a small hole in it during the night — no support
4. Cold makes the tyre grow bigger — ← Mova's choice · score 11

Why: It took the question to ask what it is done to. It chose option 4 with score 11, the only option with support. Its support: lesson 4, line 9: «Squashed air pushes back hard, which is how bike tyres and footballs work.», reached through the same lesson line as the sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «bike tyres» (+5). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 11 · ★ · wrong ✗

Which balloon will still be floating after a week?

1. A balloon blown up with breath — score 4
2. A water balloon — ← Mova's choice · score 9
3. A rubber helium balloon — score 9
4. A foil balloon — ✓ the right answer · score 9

Why: It took the question to ask who or what does it. It chose option 2 with score 9, tied with another option at 9 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 2, line 13: «Helium is lighter than air, so helium balloons float; it was first found in the Sun's light, and its name comes from the Greek for "Sun".», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same action «float» (+3); the same doer «helium balloons» (+2). The right option, 4, scored 9. · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify the substance whose presence in exhaled breath causes lime water to become milky.

1. Nitrogen — ← Mova's choice · no support
2. Helium — no support
3. Carbon dioxide — ✓ the right answer · no support
4. Oxygen — no support

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

Exam question 2 · formal language · right ✓

It is given that the air within a balloon is heated. Select the statement most accurately characterising the consequence.

1. The air expands, becomes lighter than the surrounding air, and the balloon rises — ← Mova's choice · ✓ the right answer · score 5
2. The air contracts and the balloon descends — no support
3. The air becomes heavier and more compressed, and the balloon remains wholly stationary — no support
4. The air is converted into helium — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, the only option with support. Its support: lesson 20, line 3: «Gases are made of tiny particles zooming about. Heat them and they move faster and spread out, which is why a hot-air balloon rises; cool them and they slow do…», reached through the same lesson line as the sentence the question matched. What matched: the same action «rise» (+3); the same doer «air balloon» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · right ✓

Which of the following statements most accurately characterises carbon monoxide?

1. It possesses a strong odour of rotten eggs — score 4
2. It is odourless and can prove fatal — ← Mova's choice · ✓ the right answer · score 5
3. It is visible as a white cloud — score 5
4. It is entirely harmless in enclosed spaces — score 5

Why: It took the question to ask who or what does it. It chose option 2 with score 5, tied with another option at 5 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 18, line 14: «Gas made in a closed container pushes on the walls until the weakest part gives, so reacting chemicals in a tightly closed bottle can burst it dangerously.», 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 doer «gas» (+2). · the question and its options parsed, with trees and pragmatics

Exam question 4 · formal language · right ✓

Ascertain the reason for which a helium balloon of rubber diminishes in size over several days.

1. Atmospheric pressure crushes the balloon — no support
2. The rubber absorbs the helium chemically — no support
3. Helium atoms pass through minute gaps in the rubber — ← Mova's choice · ✓ the right answer · score 3
4. Helium is converted into water vapour — no support

Why: It took the question to ask which statement is true. It chose option 3 with score 3, the only option with support. Its support: lesson 20, line 7: «Helium atoms are so small they slip through rubber, so helium balloons shrink after a few days; foil balloons last longer because their skin has smaller gaps.», reached through a sentence linked to the one the question matched. What matched: the same doer «atoms» (+2); the same circumstance (+2). Against it: a different action (counts against) (-1). · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/chemistry/20-gases-all-around-breath-and-balloons/