Mixing and dissolving

Tests: 6 of 10 right · Exam: 0 of 4 right · Kind: ★★ · Understood: 11 of 14 · Run: 2026-10-18, commit f3c23ea72

Lesson 6 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 ✗

Your friend says: "Sugar in tea is gone, it's just sweet water now, nothing left." What could prove her wrong?

1. Taste it to check that it is not sweet any more — ← Mova's choice · score 10
2. Pour it through a fine kitchen sieve to catch all the sugar — no support
3. Hold it up to the light — no support
4. Let the water evaporate and sugar is left behind — ✓ the right answer · score 10

Why: It took the question to ask who or what does it. It chose option 1 with score 10, tied with another option at 10 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 6, line 3: «The sugar plus the water make a solution; let the water evaporate and the sugar comes back.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same doer «sugar» (+4). The right option, 4, scored 10. · the question and its options parsed, with trees and pragmatics

Test 2 · ★★ · wrong ✗

"why can't I just sieve the sugar outta my squash, it's too sweet" Best answer?

1. Sieves are only for flour — ← Mova's choice · no support
2. The sugar would block the holes in the sieve — no support
3. Dissolved sugar is too small to be caught, add water instead — ✓ the right answer · no support
4. You can, but only with a wooden sieve that has very small holes — 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 · ★★ · wrong ✗

What would happen if you used ice-cold water to make a strong syrup?

1. The sugar would freeze into ice — no support
2. Much less sugar would dissolve, and slowly — ✓ the right answer · no support
3. More sugar would dissolve than in hot water — ← Mova's choice · score 4
4. It would turn into honey — no support

Why: It took the question to ask what happens next. It chose option 3 with score 4, the only option with support. Its support: lesson 6, line 14: «Gases dissolve in water too; fish breathe oxygen dissolved in the water, taking it in through their gills, and warm water holds less of it.», reached through the option's own match among the sentences about the question's things. What matched: the same action «dissolve» (+2); the same circumstance (+2). The right option, 2, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 4 · ★★ · right ✓

Why is it easier to float in the sea than in a swimming pool?

1. Salty water holds you up more than fresh water — ← Mova's choice · ✓ the right answer · score 4
2. Waves push you up all the time — no support
3. Pool water has no particles in it — no support
4. Sea water is much warmer than pool water — no support

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 6, line 10: «The Dead Sea is so salty that people float on it like corks; salty water holds you up more than fresh water.», reached through the same lesson line as the sentence the question matched. What matched: the same action «hold up» (+2); the same doer «salty water» (+2). · the question and its options parsed, with trees and pragmatics

Test 5 · ★★ · right ✓

Your cousin pours ground coffee into hot water and wonders why it is gritty. What is the reason?

1. He used too little water — score 7
2. Ground coffee only dissolves properly in water that is ice cold — score 8
3. Ground coffee does not fully dissolve, it needs a filter — ← Mova's choice · ✓ the right answer · score 9
4. The cup was not stirred clockwise — no support

Why: It took the question to ask what it is done to. It chose option 3 with score 9, against 8 for the next best. Its support: lesson 6, line 16: «Instant coffee is coffee liquid that was dried; ground coffee does not fully dissolve, so it needs a filter.», reached through the option's own match among the sentences about the question's things. What matched: it fills the role the question asks for (+3); the same action «need» (+2); the same doer «coffee» (+2); the same thing acted on «filter» (+2). · the question and its options parsed, with trees and pragmatics

Test 6 · ★★ · right ✓

A cartoon fish gasps in a pond on a scorching day and someone says "it's too sunny for its eyes". What is the real problem?

1. The fish has forgotten how to swim — no support
2. Fish are scared of sunlight and hold their breath until it goes away — no support
3. The water has turned to salt — score 6
4. Warm water holds less oxygen for the fish to breathe — ← Mova's choice · ✓ the right answer · score 10

Why: It took the question to ask what it is done to. It chose option 4 with score 10, against 6 for the next best. Its support: lesson 6, line 14: «Gases dissolve in water too; fish breathe oxygen dissolved in the water, taking it in through their gills, and warm water holds less of it.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «oxygen» (+4); the same circumstance (+4). Against it: a different action (counts against) (-2); a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 7 · ★★ · right ✓

"chucked a whole sugar cube in, still there after ages, dunno why" What would speed it up?

1. Use colder water and wait a lot longer — no support
2. Put a lid on the cup to keep the heat in — no support
3. Crush it, use hotter water and stir — ← Mova's choice · ✓ the right answer · score 8
4. Drop in a few more sugar cubes to help it — score 8

Why: It took the question to ask what it is done to. It chose option 3 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 1, line 12: «A salt grain is a tiny cube because salt's particles stack in a cube pattern; a sugar grain has flat faces too, but a different shape.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same thing acted on «tiny cube» (+4). Against it: a different doer (counts against) (-2). · the question and its options parsed, with trees and pragmatics

Test 8 · ★★ · wrong ✗

Why do sugar crystals sometimes appear at the bottom of an old jar of syrup?

1. Ants carry them in at night — no support
2. Syrup slowly turns into salt over time — no support
3. It holds more sugar than it can keep dissolved as it cools — ✓ the right answer · no support
4. The glass grows crystals — ← Mova's choice · score 2

Why: It took the question to ask why something happens (its cause). It chose option 4 with score 2, the only option with support. Its support: lesson 4, line 19: «Glass is a solid with jumbled particles; the idea that old windows are thick at the bottom because glass flows is a myth: old panes were simply made uneven, an…», reached through the cause of the sentence the question matched. What matched: the same doer «glass» (+4). Against it: a different action (counts against) (-2). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Test 9 · ★★ · right ✓

Effervescent vitamin tablets fizz in water. What do they have in common with a bath bomb?

1. They both contain soap — no support
2. They both are made of sugar only — no support
3. A dry acid and soda that react once water lets them meet — ← Mova's choice · ✓ the right answer · score 2
4. They both have air pumped into them at the factory so they fizz when opened — no support

Why: It took the question to ask who or what does it. It chose option 3 with score 2, the only option with support. Its support: lesson 6, line 15: «A bath bomb holds a dry acid and baking soda that react only when water lets them meet, making carbon dioxide bubbles.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «acid» (+2); the same circumstance (+2). Against it: a different action (counts against) (-1); a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics

Test 10 · ★★ · right ✓

Your brother says sand dissolves if you stir long enough. Is he right?

1. Only on a beach — no support
2. No, water cannot pull apart sand's strongly joined particles — ← Mova's choice · ✓ the right answer · score 5
3. Yes, if the water is very cold and you stir it the other way round — no support
4. Yes, after about an hour of stirring — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 5, the only option with support. Its support: lesson 6, line 11: «Sand does not dissolve in water, because its particles are joined too strongly for water to pull them apart; nail varnish does not dissolve in water either, bu…», reached through a sentence linked to the one the question matched. What matched: the same action «join» (+2); the same thing acted on «particles» (+2); the same property (+1). · the question and its options parsed, with trees and pragmatics

Exam question 1 · formal language · wrong ✗

Which of the following statements most accurately characterises the dissolution of sugar in water?

1. The sugar is transformed into water — no support
2. The sugar is destroyed by the water and ceases altogether to exist — ← Mova's choice · score 14
3. The sugar molecules become dispersed amongst the water molecules, remaining present — ✓ the right answer · no support
4. The sugar settles invisibly at the base of the vessel — no support

Why: It took the question to ask who or what does it. It chose option 2 with score 14, the only option with support. Its support: lesson 6, line 8: «Hot water dissolves sugar faster and can hold more of it than cold water.», reached through the remembered sentence the question matched. What matched: it fills the role the question asks for (+6); the same doer «hot water» (+4); the same thing acted on «sugar» (+4). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

Exam question 2 · formal language · wrong ✗

It is given that further salt, added to water, remains undissolved at the base of the vessel. Identify the term applicable to the solution.

1. Neutralised — ← Mova's choice · no support
2. Very dilute — no support
3. Saturated — ✓ the right answer · no support
4. Evaporated — 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 3 · formal language · wrong ✗

Select the response that is consistent with the established facts concerning the rate of dissolution of a sugar cube.

1. It is increased by cooling the water to near freezing and by leaving it entirely undisturbed — ← Mova's choice · no support
2. It is invariable whatever the conditions — no support
3. It is increased by heating, by stirring and by reduction of the cube to small grains — ✓ the right answer · no support
4. It is increased by enlarging the cube — 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 · wrong ✗

Identify the principal reason for which fish in a pond may suffer during periods of excessive heat.

1. Fish are unable to swim in warm water — no support
2. Warm water contains a greater quantity of dissolved salt — ← Mova's choice · score 3
3. Warm water retains a lesser quantity of dissolved oxygen — ✓ the right answer · no support
4. Sunlight renders pond water poisonous — no support

Why: It took the question to ask which statement is true. It chose option 2 with score 3, the only option with support. Its support: lesson 6, line 14: «Gases dissolve in water too; fish breathe oxygen dissolved in the water, taking it in through their gills, and warm water holds less of it.», reached through the same lesson line as the sentence the question matched. What matched: the same action «hold» (+2); the same doer «warm water» (+2). Against it: a different thing acted on (counts against) (-1). The right option, 3, found no support in what it remembers. · the question and its options parsed, with trees and pragmatics

This page in Markdown → https://md.mova.elamur.ai/free/en/school-run/chemistry/6-mixing-and-dissolving/