---
title: Changes you can undo and changes you can't — the lesson's questions with trees and pragmatics · Chemistry
description: The 14 test and exam questions of lesson 9 «Changes you can undo and changes you can't» of the chemistry course of Mova's primary school, each with its options, Mova's choice and the right answer, every sentence with its dependency tree and pragmatics.
---

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# Changes you can undo and changes you can't

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The 14 questions of lesson 9 «Changes you can undo and changes you can't» of the chemistry course of Mova's primary school with their options, 78 sentences, every one parsed by Mova with its syntax tree and pragmatics. How the student did on them: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/chemistry/9-changes-you-can-and-cannot-undo/).

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- [t1](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t1/) — Your friend says: "Bubbles mean a new substance, so boiling water is a chemical change." Put him right. — wrong ✗ · ★
- [t2](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t2/) — "if atoms never get destroyed, why can't I glue my burnt homework back together?" Best answer? — wrong ✗ · ★
- [t3](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t3/) — What would happen if you opened the oven far too early while a cake was rising? — right ✓ · ★
- [t4](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t4/) — A cartoon chef "un-fries" an egg by putting it in the fridge. What is wrong? — right ✓ · ★
- [t5](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t5/) — Your sister says: "A colour change always means a chemical change." Is that right? — wrong ✗ · ★
- [t6](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t6/) — Why do archaeologists find so many broken pots? — wrong ✗ · ★
- [t7](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t7/) — "can't I just scrape off the burnt bits and get my bread back?" Best answer? — right ✓ · ★
- [t8](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t8/) — Grandma's chocolate bar looks pale and grey. Your brother says it's poison. What is the truth? — wrong ✗ · ★
- [t9](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t9/) — Which of these is a change you can undo? — wrong ✗ · ★
- [t10](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/t10/) — Is boiling water a reversible change? — right ✓ · ★
- [e1](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/e1/) — Which of the following statements most accurately characterises a reversible change? — right ✓ · exam
- [e2](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/e2/) — Identify the principal reason for which the frying of an egg cannot be reversed in the kitchen. — wrong ✗ · exam
- [e3](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/e3/) — Select the response that is consistent with the established facts concerning the combustion of paper. — right ✓ · exam
- [e4](https://md.mova.elamur.ai/free/en/corpora/questions/chemistry/9-changes-you-can-and-cannot-undo/e4/) — It is given that bubbles are observed in a liquid. Determine whether this observation alone establishes that a chemical change has occurred. — right ✓ · exam

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