The fizz: vinegar, lemon and soda

Tests: 5 of 11 right · Exam: 2 of 4 right · Kind: ★★ · Understood: 7 of 15 · Run: 2026-10-18, commit f3c23ea72

Lesson 18 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 · ★★ · wrong ✗

Emma's volcano stopped fizzing. She adds more soda and nothing happens. What ran out?

1. The air — no support
2. The soda — ← Mova's choice · score 4
3. The vinegar — ✓ the right answer · score 4
4. The washing-up liquid — no support

Why: It took the question to ask who or what does it. It chose option 2 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 18, line 12: «Sherbet has a dry acid and baking soda that only react when wet, so it fizzes in your mouth and not in the packet.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+4); the same doer «dry acid» (+2). Against it: a different action (counts against) (-2). The right option, 3, scored 4. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★ · right ✓

"the science-fair volcano is EXACTLY how Vesuvius works" says Josh. What's true?

1. Real volcanoes are powered by soap — no support
2. Real volcanoes erupt melted rock and gas — ← Mova's choice · ✓ the right answer · score 4
3. He's right, a real one is just a lot bigger — no support
4. Real volcanoes use lemon juice — no support

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 18, line 9: «Real volcanoes erupt melted rock pushed by hot gases deep underground, not by vinegar and soda.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «melted rock» (+2); the same action «erupt» (+1); the same doer «real volcanoes» (+1). · the question and its options parsed, with trees and pragmatics

Test 3 · ★★ · right ✓

A cartoon shows a balloon filled from vinegar and soda floating to the moon. What would really happen?

1. It would not float, the gas is heavier than air — ← Mova's choice · ✓ the right answer · score 5
2. It would turn into vinegar — no support
3. It would float just like a helium balloon — score 3
4. It would burst into flames — no support

Why: It took the question to ask which statement is true. It chose option 1 with score 5, against 3 for the next best. Its support: lesson 18, line 10: «Carbon dioxide is heavier than air, so a balloon filled with it from the reaction does not float.», reached through the same lesson line as the sentence the question matched. What matched: the same circumstance (+3); the same property (+1); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · wrong ✗

Liam wants to put the vinegar and soda in a bottle and screw the cap on tight "to see what happens". What's the honest answer?

1. Fine, nothing happens in a closed bottle — ← Mova's choice · no support
2. Fine, the gas just disappears — no support
3. Don't: the gas builds up and can burst the bottle — ✓ the right answer · no support
4. Fine, it makes the bottle colder only — 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 ✗

"i put an egg in vinegar for 3 days and now it bounces lol how". Why?

1. The yolk turned into air — ← Mova's choice · no support
2. The egg froze in the fridge — no support
3. The vinegar slowly turned the whole egg into rubber — no support
4. The shell dissolved, only the skin holds it — ✓ 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 6 · ★★ · wrong ✗

You find a white rock on a walk. A drop of vinegar makes it fizz. What might it be?

1. A piece of granite — ← Mova's choice · no support
2. Coal — no support
3. Limestone or chalk — ✓ the right answer · no support
4. A lump of gold — 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 7 · ★★ · wrong ✗

If you did the fizz test in fridge-cold vinegar instead of warm vinegar, what would happen?

1. It would freeze into a solid foam — ← Mova's choice · no support
2. It would fizz more slowly — ✓ the right answer · no support
3. It would not fizz at all ever — no support
4. It would fizz much, much faster — 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 8 · ★★ · wrong ✗

Mia tests three amounts of soda, but uses warm vinegar for one and cold for another. What's wrong?

1. Nothing, that's a perfect test of the soda — ← Mova's choice · no support
2. She should use more soda — no support
3. She changed two things, so it isn't fair — ✓ the right answer · no support
4. She should use lemon not vinegar — 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 9 · ★★ · right ✓

"sherbet's been in me pocket all day and hasn't fizzed, is it dead?"

1. Yes, pockets kill sherbet — no support
2. Yes, sherbet goes off in an hour — no support
3. No, it only fizzes when wet in your mouth — ← Mova's choice · ✓ the right answer · score 12
4. No, it fizzes only at night — score 8

Why: It took the question to ask which statement is true. It chose option 3 with score 12, against 8 for the next best. Its support: lesson 18, line 12: «Sherbet has a dry acid and baking soda that only react when wet, so it fizzes in your mouth and not in the packet.», reached through the remembered sentence the question matched. What matched: the same action «fizz» (+4); the same doer «sherbet» (+4); the same place «mouth» (+4). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · right ✓

Why does a carbon dioxide fire extinguisher help on some fires?

1. The gas burns up the flames' fuel — no support
2. The gas pushes oxygen away from the flames — ← Mova's choice · ✓ the right answer · score 6
3. The gas cools the fire with ice — no support
4. The gas is wet and soaks the fire like a hose — no support

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 6, the only option with support. Its support: lesson 18, line 11: «Carbon dioxide pushes oxygen away from a flame, so poured over a candle it puts it out; some fire extinguishers use it.», reached through the cause of the sentence the question matched. What matched: the same thing acted on «oxygen» (+5); the same property (+3). Against it: a different action (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 11 · ★★ · right ✓

Leo does his fizz test once and gets a big result. His teacher says "do it again". Why?

1. Because tests must be done in pairs — no support
2. To check the result wasn't just luck — ← Mova's choice · ✓ the right answer · score 5
3. Because the first one was boring — no support
4. To use up the rest of the vinegar — no support

Why: It took the question to ask why something happens (its cause). It chose option 2 with score 5, the only option with support. Its support: lesson 18, line 18: «In a fair test you change only one thing and keep everything else the same, and scientists repeat tests to make sure a result was not luck.», reached through the same lesson line as the sentence the question matched. What matched: the same doer «result» (+2); the same thing acted on «luck» (+2); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Identify the gas liberated when an acid such as vinegar reacts with baking soda.

1. Oxygen — ← Mova's choice · no support
2. Hydrogen — no support
3. Nitrogen — no support
4. Carbon dioxide — ✓ 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

Exam question 2 · formal language · wrong ✗

It is given that a closed vessel contains reacting substances which produce gas. Ascertain the principal hazard.

1. The vessel may become strongly and permanently magnetised — no support
2. The vessel will become permanently cold — no support
3. The substances may turn into solid metal — ← Mova's choice · score 2
4. The pressure may rise until the vessel bursts — ✓ the right answer · no support

Why: It took the question to ask which statement is true. It chose option 3 with score 2, the only option with support. 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 option's own match among the sentences about the question's things. What matched: the same action «turn» (+1); the same doer «frozen carbon dioxide» (+1). The right option, 4, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 3 · formal language · right ✓

Which of the following statements most accurately characterises a fair test?

1. Only one factor is altered whilst all others are held constant — ← Mova's choice · ✓ the right answer · no support
2. The result is determined before the experiment begins — no support
3. The experiment is conducted on one occasion only — no support
4. All factors are altered simultaneously to save time — 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 4 · formal language · right ✓

Select the response consistent with the established facts concerning the effect of temperature upon the rate of a reaction.

1. Warmth increases the rate, as particles move faster and meet more often — ← Mova's choice · ✓ the right answer · no support
2. Warmth invariably halts the reaction completely and permanently in every case — no support
3. Cold invariably accelerates the reaction — no support
4. Temperature has no effect upon the rate of any reaction — no support

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

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/chemistry/18-the-fizz-vinegar-lemon-and-soda/