📚 Year 7 SQA Chemistry: Unit Test Mock Paper Walkthrough | Year 7 SQA 化学：单元测试模拟卷解析
This article provides a detailed walkthrough of a mock unit test paper for Year 7 SQA Chemistry. Each question is explained step by step, highlighting the key concepts and common pitfalls. Use this guide to strengthen your understanding and boost your confidence before the real test.
本文详细解析一份 Year 7 SQA 化学单元测试模拟卷。每道题目都逐步讲解，强调关键概念和常见错误。利用本指南巩固理解，并在真正考试前提升自信。
1. Introduction to the Unit Test | 单元测试简介
The Year 7 SQA Chemistry unit test typically covers states of matter, particle theory, elements, compounds and mixtures, separation methods, acids and alkalis, the pH scale, and simple chemical reactions. The mock paper includes multiple‑choice, short‑answer and extended‑response questions to reflect the actual exam format.
Year 7 SQA 化学单元测试通常涵盖物质状态、粒子理论、元素、化合物与混合物、分离方法、酸和碱、pH 标度以及简单的化学反应。这份模拟卷包含选择题、简答题和拓展题，反映真实考试形式。
2. Question 1: States of Matter | 第1题：物质的状态
Question: Which state of matter has a fixed volume but no fixed shape? Explain your answer.
题目：哪种状态的物质有固定的体积但没有固定的形状？请解释你的答案。
Answer: Liquid. The particles in a liquid are still close together (fixed volume) but can slide past each other, allowing the liquid to take the shape of its container.
答案：液体。液体中的粒子依然紧密排列（固定体积），但可以相互滑动，使液体能够呈现容器的形状。
Common mistake: Some students confuse liquid with gas. Gases have neither fixed volume nor fixed shape because their particles are far apart and move randomly.
常见错误：部分学生将液体与气体混淆。气体既没有固定体积也没有固定形状，因为其粒子相隔很远且随机运动。
3. Question 2: Particle Theory | 第2题：粒子理论
Question: Use particle theory to explain why a balloon expands when you blow air into it.
题目：请用粒子理论解释为什么给气球吹气时气球会膨胀。
Answer: When you blow air into the balloon, more gas particles enter the balloon. These particles move rapidly and collide with the inner walls, exerting pressure. The elastic material stretches, increasing the volume until the internal and external pressures balance.
答案：当你向气球内吹气时，更多气体粒子进入气球。这些粒子快速运动并与内壁碰撞，产生压力。弹性材料被拉伸，体积增大，直到内外压力平衡。
Key point: The space between particles is what changes, not the particles themselves. The number of particles per unit volume increases, leading to more frequent collisions.
关键点：变化的是粒子之间的距离，而不是粒子本身。单位体积内的粒子数量增加，导致碰撞更频繁。
4. Question 3: Elements, Compounds and Mixtures | 第3题：元素、化合物与混合物
Question: Classify each of the following as an element, compound or mixture: oxygen gas (O₂), water (H₂O), air, iron (Fe).
题目：将下列物质分类为元素、化合物或混合物：氧气 (O₂)、水 (H₂O)、空气、铁 (Fe)。
- Oxygen gas: Element – it consists of only one type of atom (oxygen atoms bonded in pairs).
- Water: Compound – made of hydrogen and oxygen chemically bonded in a fixed ratio.
- Air: Mixture – a physical blend of nitrogen, oxygen, carbon dioxide and other gases, not chemically combined.
- Iron: Element – found on the periodic table, composed solely of iron atoms.
- 氧气：元素——只由一种原子构成（氧原子成对结合）。
- 水：化合物——由氢和氧以固定比例通过化学键结合而成。
- 空气：混合物——氮气、氧气、二氧化碳等气体的物理混合，未发生化学结合。
- 铁：元素——存在于周期表中，仅由铁原子组成。
5. Question 4: Separation Techniques | 第4题：分离技术
Question: A mixture of sand and salt is given. Describe how you would obtain pure dry salt from this mixture. Name the techniques involved.
题目：现有一份沙子和食盐的混合物。请描述如何从该混合物中获得纯净干燥的食盐，并说出所涉及的技术名称。
Answer: Add water to dissolve the salt, leaving the sand undissolved. Filter the mixture to remove the sand (filtration). Then heat the salt solution to evaporate the water (evaporation or crystallisation). Finally, dry the solid salt. Techniques: dissolution, filtration, evaporation.
答案：加水溶解食盐，沙粒不溶。过滤混合物以去除沙粒（过滤）。然后加热食盐溶液使水分蒸发（蒸发或结晶）。最后干燥固体盐。技术：溶解、过滤、蒸发。
Safety tip: When evaporating, use gentle heat to avoid spitting. For pure crystals, stop heating before all water evaporates and let it cool slowly.
安全提示：蒸发时用小火加热避免迸溅。若要获得纯晶体，在水分完全蒸干前停止加热并缓慢冷却。
6. Question 5: Acids and Alkalis | 第5题：酸和碱
Question: Name two common laboratory acids and two common alkalis. State one everyday use for each.
题目：说出两种常见的实验室酸和两种常见的碱。各说明一种日常用途。
- Hydrochloric acid (HCl) – used in cleaning metal surfaces.
- Sulfuric acid (H₂SO₄) – used in car batteries.
- Sodium hydroxide (NaOH) – found in drain cleaners.
- Calcium hydroxide (Ca(OH)₂) – used to neutralise acidic soils.
- 盐酸 (HCl) – 用于清洗金属表面。
- 硫酸 (H₂SO₄) – 用于汽车电池。
- 氢氧化钠 (NaOH) – 存在于下水道清洁剂中。
- 氢氧化钙 (Ca(OH)₂) – 用于中和酸性土壤。
Note: Alkalis are soluble bases. Always handle them with care; they can be corrosive.
注意：碱是可溶的碱。操作时务必小心，它们可能具有腐蚀性。
7. Question 6: pH Scale and Indicators | 第6题：pH 标度与指示剂
Question: Complete the table using the words strong acid, weak acid, neutral, weak alkali, strong alkali.
| pH | Description |
|---|---|
| 1 | Strong acid |
| 4 | Weak acid |
| 7 | Neutral |
| 10 | Weak alkali |
| 14 | Strong alkali |
题目：用强酸、弱酸、中性、弱碱、强碱完成表格。
Explanation: The pH scale goes from 0 to 14. Values below 7 are acidic (the lower the pH, the stronger the acid). Values above 7 are alkaline (the higher the pH, the stronger the alkali). pH 7 is neutral.
解释：pH 标度从 0 到 14。小于 7 为酸性（pH 越低，酸性越强）。大于 7 为碱性（pH 越高，碱性越强）。pH 7 为中性。
8. Question 7: Chemical Reactions – Evidence | 第7题：化学反应的证据
Question: List three signs that a chemical reaction has taken place. Give an example of each.
题目：列出化学反应发生的三个迹象，并为每个迹象举一个例子。
- Colour change – when iron rusts, it turns from grey to orange‑brown.
- Gas production (effervescence) – adding vinegar to baking soda produces carbon dioxide bubbles.
- Temperature change – burning wood releases heat (exothermic).
- 颜色变化——铁生锈时由灰色变为橙棕色。
- 气体产生（冒泡）——将醋加入小苏打中产生二氧化碳气泡。
- 温度变化——燃烧木材释放热量（放热反应）。
Other signs: Precipitate formation (solid forming in a solution) or a change in smell.
其他迹象：生成沉淀（溶液中形成固体）或气味变化。
9. Question 8: Word Equations | 第8题：文字方程式
Question: Write the word equation for the reaction between magnesium and hydrochloric acid. What are the products?
题目：写出镁与盐酸反应的文字方程式。产物是什么？
magnesium + hydrochloric acid → magnesium chloride + hydrogen
镁 + 盐酸 → 氯化镁 + 氢气
Products: Magnesium chloride (a salt) and hydrogen gas. The test for hydrogen is a lighted splint giving a squeaky pop.
产物：氯化镁（一种盐）和氢气。检验氢气的方法是用点燃的木条靠近，会发出尖锐的爆鸣声。
10. Question 9: Rusting and Oxidation | 第9题：生锈与氧化
Question: Explain why iron gates rust more quickly in coastal areas. Suggest one method to prevent rusting.
题目：解释为什么沿海地区的铁门生锈更快。提出一种防锈方法。
Answer: Rusting requires both oxygen and water. Coastal air contains salt spray, which acts as an electrolyte, speeding up the electrochemical process of rust formation. To prevent rusting, paint the iron surface or apply oil/grease to block moisture and oxygen.
答案：生锈需要氧气和水。沿海空气含盐雾，盐充当电解质，加速生锈的电化学过程。防锈方法：给铁表面涂漆或涂油／脂以隔绝水分和氧气。
Alternative method: Galvanising (coating with zinc) provides sacrificial protection because zinc oxidises more readily than iron.
替代方法：镀锌（覆盖锌层）提供牺牲性保护，因为锌比铁更易氧化。
11. Final Tips for the Unit Test | 单元测试最后建议
Review the particle model and be able to draw diagrams for solids, liquids and gases. Practise writing word equations for common reactions (acid + metal, acid + carbonate). Memorise the pH scale and the colours of universal indicator. Always read questions carefully and include scientific keywords in your answers.
复习粒子模型，能画出固体、液体和气体的示意图。练习常见反应的文字方程式（酸+金属、酸+碳酸盐）。记住 pH 标度和通用指示剂的颜色。始终仔细读题，在答案中使用科学关键词。
Published by TutorHao | Chemistry Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
屏轩国际教育cambridge primary/secondary checkpoint, cat4, ukiset,ukcat,igcse,alevel,PAT,STEP,MAT, ibdp,ap,ssat,sat,sat2课程辅导，国外大学本科硕士研究生博士课程论文辅导