---
title: Identify the principal distinction between a mixture and a compound. — Molecules: when atoms join up · tree and pragmatics
description: Identify the principal distinction between a mixture and a compound. Exam question 2 of lesson 3 «Molecules: when atoms join up» of the chemistry course of Mova's primary school, with the dependency tree and pragmatics of the question and of each option; Mova's choice was right.
---

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# Exam question 2 · Molecules: when atoms join up

<!-- .ven lang=en -->
Identify the principal distinction between a mixture and a compound.

<!-- .vintro -->
**Mova's choice:** option 3 · **The right answer:** option 3 · right ✓ · **Who acts:** you · **What happens:** identify · **To what, where:** principal distinction

<!-- .vabout -->
This is exam question 2 of lesson 3 «Molecules: when atoms join up» of the chemistry course of Mova's primary school, asked in stiff, formal language. The page gives the question's syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause, then the 4 options as the student saw them, each with its tree and pragmatics. Every text is parsed by Mova itself. How the student answered it, with the score of every option and why: [the test at school](https://md.mova.elamur.ai/free/en/school-run/chemistry/3-molecules-when-atoms-join-up/#e2).

## The question {#question}

```conllu
# sent_id = question:chemistry:3-molecules-when-atoms-join-up:e2:1
# text = Identify the principal distinction between a mixture and a compound.
1	Identify	identify	VERB	VB	Mood=Imp|VerbForm=Fin	0	root	_	_
2	the	the	DET	DT	Definite=Def|PronType=Art	4	det	_	_
3	principal	principal	ADJ	JJ	Degree=Pos	4	amod	_	_
4	distinction	distinction	NOUN	NN	Number=Sing	1	obj	_	_
5	between	between	ADP	IN	_	7	case	_	_
6	a	a	DET	DT	Definite=Ind|PronType=Art	7	det	_	_
7	mixture	mixture	NOUN	NN	Number=Sing	4	nmod	_	_
8	and	and	CCONJ	CC	_	10	cc	_	_
9	a	a	DET	DT	Definite=Ind|PronType=Art	10	det	_	_
10	compound	compound	NOUN	NN	Number=Sing	7	conj	_	SpaceAfter=No
11	.	.	PUNCT	.	_	1	punct	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **identify** | imperative | you *not said here* | the principal distinction |  |  |  | between a mixture and a compound | vn characterize-29.2-1-1 «NP V NP S\_ING»: agent=Agent distinction=Theme |

<!-- .note -->
One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

## The options {#options}

### Option 1 {#o1}

<!-- .ven lang=en -->
A mixture contains a single element only, whereas a compound contains a great many elements

<!-- fold The tree, 15 words -->
```conllu
# sent_id = question:chemistry:3-molecules-when-atoms-join-up:e2:o1:1
# text = A mixture contains a single element only, whereas a compound contains a great many elements
1	A	a	DET	DT	Definite=Ind|PronType=Art	2	det	_	_
2	mixture	mixture	NOUN	NN	Number=Sing	3	nsubj	_	_
3	contains	contain	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	a	a	DET	DT	Definite=Ind|PronType=Art	6	det	_	_
5	single	single	ADJ	JJ	Degree=Pos	6	amod	_	_
6	element	element	NOUN	NN	Number=Sing	3	obj	_	_
7	only	only	ADV	RB	_	6	advmod	_	SpaceAfter=No
8	,	,	PUNCT	,	_	12	punct	_	_
9	whereas	whereas	SCONJ	IN	_	12	mark	_	_
10	a	a	DET	DT	Definite=Ind|PronType=Art	11	det	_	_
11	compound	compound	NOUN	NN	Number=Sing	12	nsubj	_	_
12	contains	contain	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	3	conj	_	_
13	a	a	DET	DT	Definite=Ind|PronType=Art	16	det	_	_
14	great	great	ADJ	JJ	Degree=Pos	16	amod	_	_
15	many	many	ADJ	JJ	Degree=Pos	16	amod	_	_
16	elements	element	NOUN	NNS	Number=Plur	12	obj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **contain** | present | a mixture | a single element |  |  |  |  | vn comprise-107.2-2 «NP V NP»: agent=Pivot element=Theme |
| 2 | **contain** | present | a compound | a great many elements |  |  |  |  | vn comprise-107.2-2 «NP V NP»: agent=Pivot element=Theme |

### Option 2 {#o2}

<!-- .ven lang=en -->
A compound is invariably liquid, whereas a mixture is invariably solid

```conllu
# sent_id = question:chemistry:3-molecules-when-atoms-join-up:e2:o2:1
# text = A compound is invariably liquid, whereas a mixture is invariably solid
1	A	a	DET	DT	Definite=Ind|PronType=Art	2	det	_	_
2	compound	compound	NOUN	NN	Number=Sing	5	nsubj	_	_
3	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	5	cop	_	_
4	invariably	invariably	ADV	RB	_	5	advmod	_	_
5	liquid	liquid	ADJ	JJ	Degree=Pos	0	root	_	SpaceAfter=No
6	,	,	PUNCT	,	_	12	punct	_	_
7	whereas	whereas	SCONJ	IN	_	12	mark	_	_
8	a	a	DET	DT	Definite=Ind|PronType=Art	9	det	_	_
9	mixture	mixture	NOUN	NN	Number=Sing	12	nsubj	_	_
10	is	be	AUX	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	12	cop	_	_
11	invariably	invariably	ADV	RB	_	12	advmod	_	_
12	solid	solid	ADJ	JJ	Degree=Pos	5	conj	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **is** | present | a compound |  |  |  |  | invariably, liquid *property* | tree rules |
| 2 | **is** | present | a mixture |  |  |  |  | invariably, solid *property* | tree rules |

### Option 3 · ← Mova's choice · ✓ the right answer {#o3}

<!-- .ven lang=en -->
In a compound the constituent atoms are chemically joined, whereas in a mixture they are not

<!-- fold The tree, 16 words -->
```conllu
# sent_id = question:chemistry:3-molecules-when-atoms-join-up:e2:o3:1
# text = In a compound the constituent atoms are chemically joined, whereas in a mixture they are not
1	In	in	ADP	IN	_	3	case	_	_
2	a	a	DET	DT	Definite=Ind|PronType=Art	3	det	_	_
3	compound	compound	NOUN	NN	Number=Sing	9	obl	_	_
4	the	the	DET	DT	Definite=Def|PronType=Art	6	det	_	_
5	constituent	constituent	NOUN	NN	Number=Sing	6	compound	_	_
6	atoms	atom	NOUN	NNS	Number=Plur	9	nsubj:pass	_	_
7	are	be	AUX	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	9	aux:pass	_	_
8	chemically	chemically	ADV	RB	_	9	advmod	_	_
9	joined	join	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	0	root	_	SpaceAfter=No
10	,	,	PUNCT	,	_	11	punct	_	_
11	whereas	whereas	ADV	RB	_	9	advmod	_	_
12	in	in	ADP	IN	_	14	case	_	_
13	a	a	DET	DT	Definite=Ind|PronType=Art	14	det	_	_
14	mixture	mixture	NOUN	NN	Number=Sing	9	obl	_	_
15	they	they	PRON	PRP	Case=Nom|Number=Plur|Person=3|PronType=Prs	16	nsubj	_	_
16	are	be	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	9	conj	_	_
17	not	not	PART	RB	Polarity=Neg	16	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **join** | present · passive |  | the constituent atoms |  | a compound |  | in a mixture; chemically, whereas *property* | vn mix-22.1-2-1 «NP V NP»: subject=Patient |
| 2 | **not** **does** | present | atoms *= atom* |  |  |  |  |  | vn exist-47.1 «NP V»: agent=Theme |

### Option 4 {#o4}

<!-- .ven lang=en -->
A compound may be separated by a magnet, whereas a mixture may not

```conllu
# sent_id = question:chemistry:3-molecules-when-atoms-join-up:e2:o4:1
# text = A compound may be separated by a magnet, whereas a mixture may not
1	A	a	DET	DT	Definite=Ind|PronType=Art	2	det	_	_
2	compound	compound	NOUN	NN	Number=Sing	10	nsubj	_	_
3	may	may	AUX	MD	VerbForm=Fin	5	aux	_	_
4	be	be	AUX	VB	VerbForm=Inf	5	aux:pass	_	_
5	separated	separate	VERB	VBN	Tense=Past|VerbForm=Part|Voice=Pass	2	acl	_	_
6	by	by	ADP	IN	_	8	case	_	_
7	a	a	DET	DT	Definite=Ind|PronType=Art	8	det	_	_
8	magnet	magnet	NOUN	NN	Number=Sing	5	obl	_	SpaceAfter=No
9	,	,	PUNCT	,	_	2	punct	_	_
10	whereas	wherea	VERB	VBZ	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
11	a	a	DET	DT	Definite=Ind|PronType=Art	12	det	_	_
12	mixture	mixture	NOUN	NN	Number=Sing	13	nsubj	_	_
13	may	may	AUX	MD	VerbForm=Fin	10	ccomp	_	_
14	not	not	PART	RB	Polarity=Neg	13	advmod	_	_
```

<!-- .fr -->
| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **separate** | may · passive | a magnet | a compound *not said here* |  |  |  |  | vn separate-23.1-1-1 «NP V»: agent=Patient |
| 2 | **wherea** | present | a compound |  |  |  |  |  | tree rules |

<!-- div src -->

**Text:** the tests of Mova's primary school, written for Mova (`world/data/school/`), as the course runner gave them to the student. **Trees:** Mova's own parse — the `en` model on the CPU, when the site is built — not checked by a teacher; they may be wrong. **Frames:** Mova's frames reader (`prag`), each text read on its own. Elamur Cosmic License.

<!-- /div -->

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