Oil and water, and things that won't mix
Tests: 6 of 10 right · Exam: 1 of 4 right · Kind: ★ · Understood: 7 of 14 · Run: 2026-10-18, commit f3c23ea72
Lesson 7 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 ✓
Your friend says: "If I shake oil and water hard enough they'll stay mixed forever." What actually happens?
- 1. They turn into a solid — no support
- 2. They mix for a moment, then separate again — ← Mova's choice · ✓ the right answer · score 4
- 3. They both turn into gas — no support
- 4. They stay mixed together forever and never come apart — score 2
Why: It took the question to ask which statement is true. It chose option 2 with score 4, against 2 for the next best. Its support: lesson 7, line 3: «Shake a bottle of salad dressing and the oil breaks into tiny droplets for a while, but the droplets soon join up again.», reached through the option's own match among the sentences about the question's things. What matched: the same action «break» (+2); the same doer «oil» (+2). · the question and its options parsed, with trees and pragmatics
Test 2 · ★ · right ✓
"why's milk white anyway, it's just water innit" Best answer?
- 1. Cows only drink white water — no support
- 2. It is white because it is cold — score 4
- 3. It has white paint added to it at the farm before it is bottled — no support
- 4. It is an emulsion: tiny fat drops in water scatter light — ← Mova's choice · ✓ the right answer · score 5
Why: It took the question to ask why something happens (its cause). It chose option 4 with score 5, against 4 for the next best. Its support: lesson 7, line 9: «Mayonnaise is an emulsion: tiny oil droplets held apart in egg yolk and lemon juice; milk is an emulsion of tiny fat drops in water, and the drops scatter ligh…», reached through the same lesson line as the sentence the question matched. What matched: the same doer «milk» (+2); the same thing acted on «emulsion» (+2); the same light verb (be, have, do, get, go) (+1). · the question and its options parsed, with trees and pragmatics
Test 3 · ★ · wrong ✗
What would happen if you left a lava lamp switched off?
- 1. The blobs would keep rising and falling forever — ← Mova's choice · no support
- 2. The lamp would get hot and explode — no support
- 3. The wax would dissolve in the liquid — no support
- 4. The wax would sit at the bottom — ✓ 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 4 · ★ · wrong ✗
A cartoon shows rescuers cleaning an oily seabird with plain cold water. What should they use instead?
- 1. Nothing, oil falls off by itself — ← Mova's choice · no support
- 2. Sand, which scrubs the oil away — no support
- 3. Washing-up liquid, which lifts the oil off — ✓ the right answer · no support
- 4. Vinegar, which dissolves the oil but also the feathers — 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 · ★ · right ✓
Why do ducks keep preening with their beaks?
- 1. To count their feathers — no support
- 2. To pick off and eat the insects that live on the water — no support
- 3. To dry their feathers with their breath — no support
- 4. To spread oil over their feathers and keep waterproof — ← Mova's choice · ✓ the right answer · score 6
Why: It took the question to ask why something happens (its cause). It chose option 4 with score 6, the only option with support. Its support: lesson 7, line 16: «Ducks spread oil from a gland near the tail over their feathers, so water runs off; that is why they preen so much.», reached through the same lesson line as the sentence the question matched. What matched: the same action «spread» (+2); the same doer «ducks» (+2); the same thing acted on «oil» (+2). · the question and its options parsed, with trees and pragmatics
Test 6 · ★ · right ✓
Your gran pours bacon fat down the sink. What's the risk?
- 1. It cleans the pipes — no support
- 2. It sets in the pipes and helps build blockages called fatbergs — ← Mova's choice · ✓ the right answer · score 6
- 3. It helps the pipes stay warm — no support
- 4. It turns into water once it reaches the drain under the street — no support
Why: It took the question to ask what it is done to. It chose option 2 with score 6, the only option with support. Its support: lesson 7, line 17: «Fat from cooled soup rises and sets on top; poured down the sink it hardens in pipes and helps build huge blockages called "fatbergs".», 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 «build» (+2); the same thing acted on «huge blockages» (+2). Against it: a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics
Test 7 · ★ · right ✓
In a tower of honey, water and oil, a grape sinks through oil and water and rests on the honey. Why?
- 1. Grapes always sink to the very bottom — no support
- 2. The grape is sticky, and the honey grabs it and holds it on top — no support
- 3. The grape is denser than water and oil but less dense than honey — ← Mova's choice · ✓ the right answer · score 3
- 4. The grape is lighter than oil — score 2
Why: It took the question to ask why something happens (its cause). It chose option 3 with score 3, against 2 for the next best. Its support: lesson 7, line 6: «Oil and water do not mix; they form two layers with oil on top, because oil is less dense than water.», reached through the option's own match among the sentences about the question's things. What matched: the same property (+2); the same circumstance (+1); the same light verb (be, have, do, get, go) (+1). Against it: a different doer (counts against) (-1). · the question and its options parsed, with trees and pragmatics
Test 8 · ★ · wrong ✗
"pan's greasy as hell, cold water does nothing" Best fix?
- 1. Scrub it with salt and cold water — ← Mova's choice · score 3
- 2. Use warm water and soap — ✓ the right answer · score 3
- 3. Just wipe it with a dry cloth — no support
- 4. Use more cold water, faster — score 3
Why: It took the question to ask which statement is true. It chose option 1 with score 3, tied with another option at 3 (the first shown, or the one claiming less beyond what it knows, wins). Its support: lesson 6, line 9: «Water can hold only a certain amount of salt; after that it is saturated and extra salt settles at the bottom.», reached through the option's own match among the sentences about the question's things. What matched: the same thing acted on «water» (+2); the same circumstance (+2). Against it: a different action (counts against) (-1). The right option, 2, scored 3. · the question and its options parsed, with trees and pragmatics
Test 9 · ★ · wrong ✗
Why do the rainbow colours on a puddle swirl and move?
- 1. The puddle is full of tiny fish swimming round and round under the top — ← Mova's choice · no support
- 2. The ground underneath is changing colour — no support
- 3. The oil film keeps changing thickness as it spreads and drifts — ✓ the right answer · no support
- 4. Rain falls in coloured drops — 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 10 · ★ · right ✓
Your little sister thinks mayonnaise is "just oil". What else holds it together?
- 1. Egg yolk, whose molecules sit around each oil droplet — ← Mova's choice · ✓ the right answer · score 4
- 2. Glue made from vinegar — no support
- 3. Frozen water from the fridge, which keeps the oil in place — score 4
- 4. Lots of sugar — no support
Why: It took the question to ask who or what does it. 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 7, line 4: «Egg yolk can keep the droplets apart for good: its molecules have one end that likes water and one that likes oil, which is how thick, creamy mayonnaise is mad…», 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 «egg yolk» (+2). Against it: a different action (counts against) (-1). · the question and its options parsed, with trees and pragmatics
Exam question 1 · formal language · right ✓
Which of the following statements most accurately characterises the behaviour of oil upon water?
- 1. The oil forms a distinct layer upon the surface, being less dense than water — ← Mova's choice · ✓ the right answer · no support
- 2. The oil dissolves wholly within the water — no support
- 3. The oil is converted to water upon contact — no support
- 4. The oil descends to the base of the vessel, being of greater density than water — 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
Exam question 2 · formal language · wrong ✗
Identify the principal function of egg yolk in the preparation of mayonnaise.
- 1. It supplies the greater part of the oil of which mayonnaise consists — ← Mova's choice · no support
- 2. It solidifies the oil by cooling — no support
- 3. Its molecules maintain the separation of minute droplets of oil — ✓ the right answer · no support
- 4. It renders the oil wholly soluble in water — 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 ✗
It is given that honey, water and oil are introduced into a single vessel. Ascertain the liquid which shall occupy the lowest position.
- 1. The oil — ← Mova's choice · no support
- 2. The water — no support
- 3. Honey — ✓ the right answer · no support
- 4. None, the liquids mixing uniformly — 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 ✗
Select the response that is consistent with the established facts concerning the disposal of cooking fat into domestic drainage.
- 1. It evaporates entirely before reaching the sewer — ← Mova's choice · no support
- 2. It dissolves harmlessly and completely in the water of the drains — no support
- 3. It improves the flow of water through pipes — no support
- 4. It solidifies within pipes and contributes to severe blockages — ✓ the right answer · 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/7-oil-and-water/