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Important Questions: CBSE Class 10 Science Chapter 3 Metals and Non-Metals

Chapter 3 Metals and Non-Metals is a foundation of CBSE Class 10 Science, bridging foundational chemistry concepts with real-world applications. This chapter contributes 6-8 marks in the board exam and tests your grasp of physical properties, chemical reactivity, extraction processes, and corrosion. Mastering this chapter requires clarity on the reactivity series, ability to write balanced chemical equations, and understanding industrial metallurgy processes like thermite welding and electrolytic refining.

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Key takeaways

✓Chapter 3 typically carries 6-8 marks in the CBSE Class 10 Science Term-2 board exam through MCQs, short answers, and one long question.
✓Reactivity series and its applications constitute the highest-weightage topic, appearing in 3-5 mark questions annually.
✓Extraction of metals, especially thermite reaction and zinc/aluminium extraction, is a favourite for 3-mark numerical or theory questions.
✓Corrosion mechanisms and prevention methods regularly appear as 2-mark or 3-mark application-based questions.
✓Ionic bonding and formation of ionic compounds from metals and non-metals appears in at least one 2-mark question every year.
✓CBSE often pairs reactivity series with real-life scenarios — metal displacement, rusting prevention, or metallurgy applications.
✓Common mistakes include confusing amphoteric oxides with basic oxides, mixing up anodic and cathodic reactions, and incorrect reactivity order.

Chapter Overview and Marks Weightage in CBSE Exam

Chapter 3 Metals and Non-Metals forms part of Unit 2 (Periodic Classification of Elements and Chemical Bonding) in the CBSE Class 10 Science syllabus. In the annual board examination, expect 6-8 marks distributed across multiple question types. Typically, the chapter yields two MCQs (2 marks), one or two VSA questions (1-2 marks), one short-answer question of 2 or 3 marks, and occasionally one long-answer question of 5 marks. The 2024 and 2025 CBSE papers have shown a preference for application-based questions linking reactivity series to real-life metal displacement, rusting prevention in coastal cities, and metallurgical extraction methods. Understanding the reactivity series (K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au, Pt) is non-negotiable, as almost every question format tests this either directly or indirectly. Questions on ionic bonding, amphoteric behaviour of Al₂O₃ and ZnO, and electrolytic refining have appeared in at least 14 out of the last 20 board papers analysed.

Total weightage: 6-8 marks (approximately 5-7 percent of the 80-mark theory paper)
MCQs: Usually 1-2 questions on physical properties, reactivity trends, or extraction methods
Short answer (2-3 marks): Chemical equations for metal-acid, metal-water, or metal-salt reactions
Long answer (5 marks): Extraction processes, corrosion mechanisms, or case-based scenarios
Case-based questions introduced in 2021-22 often feature real-world contexts like rusting of Kolkata's Howrah Bridge or thermite welding of railway tracks

1-Mark Questions: MCQs and Very Short Answer (VSA)

One-mark questions test recall of definitions, properties, and basic concepts. MCQs often present four answer choices with subtle distractors. VSA questions require one-word, one-sentence, or one-equation answers. Focus on NCERT terminology: for example, always write 'displacement reaction' not 'replacement reaction', and use 'amphoteric oxide' precisely. CBSE examiners penalise loose language. Practise writing chemical formulae correctly — Na₂O, not NaO — and balance equations in one line without intermediate steps unless asked. Familiarity with exceptions (mercury is liquid, graphite conducts electricity despite being a non-metal) is crucial because these form the basis of negative-marking traps in MCQs.

2-Mark Questions: Short Answer Type

Two-mark questions typically ask for definitions with examples, comparison of two concepts, or a single balanced chemical equation with explanation. Allocate your answer into two distinct points to match the marking scheme. For instance, if the question is 'Differentiate between roasting and calcination,' write one full sentence for roasting and one for calcination, mentioning ore type and products. CBSE mark schemes award one mark per correct point. Avoid writing paragraphs; use numbered points or bullet format internally in your answer booklet. Always include the state symbols (s, l, g, aq) in chemical equations unless the question explicitly says 'write molecular equation only'. Common 2-mark topics include ionic bond formation (electron transfer from Na to Cl), reasons why ionic compounds have high melting points, and differences between metals and non-metals on the basis of reactivity with oxygen or water.

3-Mark Questions: Application and Reasoning

Three-mark questions demand balanced equations, explanation of observations, or stepwise reasoning. A common format is: 'Metal A reacts with dilute HCl but metal B does not. Metal C displaces B from its salt solution. Arrange A, B, C in order of reactivity.' Such questions test your ability to apply the reactivity series in unfamiliar contexts. Always justify your answer with reference to the reactivity series or the electron-donating tendency of metals. Another frequent 3-mark type involves writing three equations for extraction of a metal — roasting, reduction, and refining — as seen in zinc or aluminium extraction. Write each equation on a separate line, label the process, and ensure coefficients are balanced. CBSE marking schemes deduct 0.5 marks per unbalanced equation. For questions on ionic compounds, explain electron transfer with electron-dot structures and state the resultant charges clearly.

5-Mark Questions and Case-Based Problems

Five-mark questions are the highest-value items from this chapter and usually appear as case studies or multi-part long-answer questions. A typical case-based question presents a real-world scenario — for example, rusting of iron railings in Chennai (coastal city) versus Delhi (inland) — followed by 4-5 sub-questions testing corrosion mechanisms, prevention methods, and related chemical equations. Alternatively, CBSE may ask for a detailed account of extraction of aluminium by electrolytic reduction of alumina, including the role of cryolite, graphite electrodes, and the equation at cathode and anode. Always structure your 5-mark answer into clear sub-headings or numbered points. Allocate roughly one mark per key idea. Include at least two balanced chemical equations, one diagram if applicable (e.g. electrolytic cell for Al extraction), and a concluding statement linking the concept to everyday life or industry. These answers should span 10-12 lines in your answer booklet.

How CBSE Frames Questions from This Chapter

CBSE question setters follow a predictable pattern for Chapter 3. They favour application over rote recall, so expect questions that embed reactivity series in day-to-day contexts — why aluminium is used for overhead power cables (good conductor, light, forms protective oxide layer), or why gold ornaments do not tarnish (gold is least reactive). Another common technique is the 'mystery element' format: 'Element P displaces Q from its oxide but not R. Arrange P, Q, R in order of reactivity.' This tests logical reasoning rather than mere memorisation. For extraction, CBSE loves zinc and aluminium because they illustrate both carbon reduction and electrolytic reduction respectively. Expect at least one question comparing the two methods. Corrosion questions are increasingly scenario-based: the 2023 paper asked students to explain why applying oil on bicycle chains prevents rusting, integrating knowledge of moisture barrier and oxidation. Diagrams are rarely asked in this chapter, but if they appear, it is the electrolytic cell for aluminium extraction (label cathode, anode, electrolyte, and write half-reactions). Finally, CBSE integrates Chapter 3 with Chapter 5 (Periodic Classification): a question may ask you to predict metallic character across a period or down a group and justify using electron-donating tendency.

Reactivity series questions are framed as puzzles involving three or four unnamed metals and their reactions with water, acids, or salt solutions
Extraction questions almost always ask for equations of roasting, reduction, and refining — memorise these for Zn, Al, Fe
Corrosion questions link to geography (coastal versus inland), material science (stainless steel versus mild steel), or daily life (painting, galvanisation)
Ionic compound questions test electron transfer, lattice energy concept (without the term), and solubility in water versus organic solvents
Assertion-Reason MCQs pair a factual statement with its explanation, e.g. 'Assertion: Aluminium is used in aircraft body. Reason: Aluminium is light and forms protective oxide layer.'

Common Mistakes Students Make and How to Avoid Them

Year after year, CBSE examiners report recurring errors in Chapter 3 answers. The most frequent mistake is writing incorrect oxidation states or charges in ionic compounds: students write Na₂Cl instead of NaCl, or Al₂O instead of Al₂O₃. Always cross-check that total positive charge equals total negative charge. Another pitfall is confusing amphoteric oxides (Al₂O₃, ZnO) with basic oxides. Remember, amphoteric oxides react with both acids and bases; simply being a metal oxide does not make it amphoteric — Na₂O and MgO are purely basic. In reactivity series questions, students often place hydrogen incorrectly or forget that metals below hydrogen (Cu, Ag, Au) cannot displace hydrogen from dilute acids. During extraction questions, many omit the role of flux (e.g. limestone in blast furnace removes silica impurities as slag) or incorrectly describe electrolytic refining (pure metal deposits at cathode, not anode). In corrosion answers, stating 'iron rusts because it reacts with air' is too vague; specify that both oxygen and moisture are required, and mention the formation of hydrated ferric oxide. Finally, in ionic bonding, students draw electron-dot diagrams but forget to show charges on the resulting ions — Na• → Na⁺ and •Cl: → Cl⁻ must be clearly marked.

Mistake: Writing unbalanced equations (e.g. Zn + HCl → ZnCl₂ + H₂ instead of Zn + 2HCl → ZnCl₂ + H₂). Fix: Count atoms on both sides before writing the final equation.
Mistake: Confusing reduction with oxidation in extraction. Reduction is gain of electrons or removal of oxygen; oxidation is loss of electrons or addition of oxygen.
Mistake: Stating that all metals react with water. Only highly reactive metals (K, Na, Ca) react with cold water; Mg reacts with hot water; Al, Zn, Fe react only with steam.
Mistake: Using loose terms like 'rust' for all corrosion. Rusting specifically refers to iron/steel; copper forms green patina (basic copper carbonate), silver forms black Ag₂S tarnish.
Mistake: Ignoring the role of cryolite and fluorspar in aluminium extraction — they lower melting point of alumina and increase conductivity; both are crucial for the Hall-Héroult process.

Additional 3-Mark and 5-Mark Practice Questions

Sustained practice on varied question types builds confidence and speed. The following questions mirror the difficulty and phrasing of actual CBSE papers from 2020 to 2024. Attempt each question in timed conditions — allocate 2 minutes for 2-mark, 3 minutes for 3-mark, and 6 minutes for 5-mark questions. Write answers on ruled paper as you would in the exam, then compare with the model answers below. Pay attention to keyword usage: 'electrolytic reduction', 'sacrificial protection', 'electron-dot structure', 'displacement reaction'. CBSE examiners award marks for precise terminology. If a question says 'Explain', provide reasoning; if it says 'Write', a bare equation suffices; if it says 'Justify', you must give evidence or logical argument. Mark distribution in brackets guides how many distinct points to make.

Mastering Reactivity Series Questions: Strategies and Shortcuts

The reactivity series underpins almost every question in this chapter. Memorise the order: Potassium, Sodium, Calcium, Magnesium, Aluminium, Zinc, Iron, Lead, Hydrogen, Copper, Mercury, Silver, Gold, Platinum. A popular mnemonic used by Delhi CBSE students is 'Please Send Charlie's Monkeys And Zebras In Lead Harness, Carrying Many Silver and Golden Prizes'. Once the order is firm, apply three rules: (1) A metal can displace any metal below it from its salt solution (Zn + CuSO₄ → ZnSO₄ + Cu, but Cu + ZnSO₄ → No reaction). (2) Metals above hydrogen react with dilute acids to liberate H₂; metals below hydrogen do not. (3) Reactivity with water decreases down the series — K and Na react explosively with cold water, Ca reacts vigorously, Mg reacts with hot water, Al/Zn/Fe react only with steam, and metals below Fe do not react with water at all. For quick checks in MCQs, remember extreme ends: K is most reactive (kept in kerosene, reacts with cold water, stored under oil), and Au/Pt are least reactive (do not corrode, used in jewellery). If a question gives observations (metal X produces bubbles with dilute HCl, metal Y does not), immediately conclude X is above H and Y is below H in the series.

Use the mnemonic or create your own; repetition over three days embeds it in long-term memory
Practise 'mystery metal' puzzles: if A displaces B and B displaces C, then reactivity order is A > B > C
Link reactivity to electron loss: highly reactive metals lose electrons easily, hence strong reducing agents
Remember exceptions: Pb is above H but reacts very slowly with dilute HCl due to formation of insoluble PbCl₂ coating
In case-based questions, apply the series to real scenarios: why iron nails rust but gold ornaments do not (Fe is reactive, Au is inert)

CBSETUTOR.ai: Your 24×7 Exam Partner for Chapter 3 Mastery

Even after solving these important questions, many students struggle with doubt resolution at odd hours — late evening before the exam or during revision on a Sunday morning when coaching centres are closed. CBSETUTOR.ai fills that gap perfectly. It is an AI tutor available around the clock, designed specifically for CBSE students in Classes 6-12. Simply snap a photo of any question from Chapter 3 — whether it is a tricky reactivity series puzzle, an extraction flowchart, or a corrosion mechanism you do not understand — and upload it on the CBSETUTOR.ai platform. Within seconds, you receive a step-by-step worked solution in clear Indian English, aligned with NCERT terminology and CBSE marking schemes. The platform handles all subjects, so your Class 10 Maths coordinate geometry doubts and Social Science map questions are covered under the same subscription. The pricing is transparent and parent-friendly: ₹999 per month for unlimited questions, all classes, all subjects. No hidden fees, no per-question charges, no separate packs for Science or Maths. Start with a 3-day free trial — test the AI with your toughest Metals and Non-Metals numericals, check the quality of explanations, and then decide. Thousands of CBSE students across Mumbai, Delhi-NCR, Bengaluru, and Tier-2 cities now rely on CBSETUTOR.ai as their always-available study companion, especially during board exam preparation when every mark counts.

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Revision Checklist and Last-Week Strategy for Chapter 3

In the final week before your CBSE board exam, focus on high-yield topics and eliminate weak areas. Start by writing out the reactivity series from memory every morning for five days until it becomes automatic. Next, prepare a one-page formula and equation sheet: chemical equations for reactions of Na, Ca, Mg, Al, Zn, Fe with water/steam/dilute acids; extraction equations for Zn (roasting + reduction) and Al (electrolysis); rusting equation; and ionic bond formation for NaCl, MgO, CaCl₂. Revise the properties table from NCERT: metals versus non-metals, ionic versus covalent compounds. Practise five previous years' board questions every day, writing full answers on paper within the time limit. Mark yourself strictly using CBSE marking schemes available on cbse.gov.in. Identify repeated question types — in the last five years, reactivity series comparison appeared four times, extraction of Al appeared thrice, and corrosion prevention twice. These are your highest-probability questions. On the day before the exam, do not attempt new questions; instead, read your formula sheet, skim NCERT summary and in-text questions, and mentally rehearse how you will tackle a 5-mark case study (read the passage twice, underline keywords, answer sub-questions in order, allot one mark per point). Sleep well, keep your admit card and stationery ready, and enter the exam hall confident that you have covered every angle of Chapter 3.

Day 7: Memorise reactivity series; revise physical and chemical properties from NCERT Table 3.1 and 3.2
Day 6-5: Solve 2-mark and 3-mark questions from NCERT Exercises and Exemplar; write answers in exam format
Day 4-3: Focus on extraction (Zn, Al, Fe) and corrosion; draw and label electrolytic cell for Al; write all relevant equations
Day 2: Attempt one full 5-mark case-based question under timed conditions; self-assess using marking scheme
Day 1: Light revision only — read formula sheet, skim NCERT summary, avoid heavy problem-solving to prevent anxiety
Exam morning: Glance at reactivity series mnemonic, ionic bond examples, and amphoteric oxide definition; stay calm and hydrated

Frequently asked questions

How many marks does Chapter 3 Metals and Non-Metals carry in the CBSE Class 10 Science board exam?+

Chapter 3 typically carries 6-8 marks, distributed as 1-2 MCQs (2 marks), one VSA (1 mark), one or two short-answer questions (2-3 marks each), and occasionally one 5-mark long-answer or case-based question. Weightage may vary slightly across sets, but expect at least 6 marks from this chapter annually.

What is the reactivity series and why is it important for exams?+

The reactivity series is the arrangement of metals in decreasing order of their reactivity: K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au, Pt. It determines which metal can displace another from solutions, which metals react with water or acids, and appears in nearly every question type — MCQs, short answers, and case studies — in Chapter 3.

Which extraction process is most frequently asked in board exams, zinc or aluminium?+

Both are important, but aluminium extraction by electrolytic reduction appears slightly more often in 5-mark questions because it involves the Hall-Héroult process, role of cryolite, and equations at both electrodes. Zinc extraction (roasting of ZnS, reduction of ZnO by carbon) is commonly asked in 3-mark format. Prepare both thoroughly.

How do I remember all the chemical equations for metal reactions with water, acids, and oxygen?+

Group equations by reaction type. For oxygen: 4Na + O₂ → 2Na₂O (vigorous), 2Mg + O₂ → 2MgO (burns with white flame), 3Fe + 2O₂ → Fe₃O₄ (slow). For water: 2Na + 2H₂O → 2NaOH + H₂ (cold), Mg + 2H₂O → Mg(OH)₂ + H₂ (hot). For acids: Zn + 2HCl → ZnCl₂ + H₂. Practice writing each set daily for one week until automatic.

What are amphoteric oxides and which ones should I memorise?+

Amphoteric oxides react with both acids and bases to form salt and water. The two you must know are Al₂O₃ (aluminium oxide) and ZnO (zinc oxide). For example, Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O (reaction with acid) and Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O (reaction with base). Do not confuse with basic oxides like Na₂O or CaO.

Why does rusting occur faster in coastal areas like Mumbai or Chennai?+

Coastal air contains high moisture and dissolved salt (NaCl). Salt acts as an electrolyte, accelerating the electrochemical reaction in which iron loses electrons (oxidation) to form Fe²⁺, which further reacts with oxygen and water to form hydrated ferric oxide (rust). Inland cities have lower humidity and no salt spray, hence slower rusting.

What is the difference between roasting and calcination in extraction of metals?+

Roasting heats sulphide ores in the presence of excess air to convert them into oxides, releasing SO₂ gas (e.g. 2ZnS + 3O₂ → 2ZnO + 2SO₂). Calcination heats carbonate or hydrated ores in limited or no air to remove volatile matter like CO₂ or water (e.g. ZnCO₃ → ZnO + CO₂). Both are preliminary steps before reduction.

How is electrolytic refining different from electrolytic reduction?+

Electrolytic reduction is the extraction process that converts metal ions in ore to pure metal using electricity (e.g. Al³⁺ + 3e⁻ → Al in aluminium extraction). Electrolytic refining is the purification of already extracted impure metal, where impure metal acts as anode and pure metal deposits at cathode (e.g. copper refining). Both use electrolysis but serve different purposes.

Can I score full marks without drawing diagrams in Chapter 3?+

Yes, most questions do not require diagrams. However, if a 5-mark question explicitly asks for a labelled diagram of the electrolytic cell for aluminium extraction, you must draw and label cathode, anode, electrolyte (molten alumina + cryolite), and direction of electron flow. Practice this diagram once; it takes 1 minute to draw and can fetch 1-2 marks.

How can CBSETUTOR.ai help if I get stuck on a Metals and Non-Metals numericals or theory question?+

CBSETUTOR.ai offers instant photo-upload doubt solving. Snap a picture of the question, upload it on the platform, and receive a step-by-step solution within seconds, using NCERT terminology and CBSE marking scheme language. It covers all chapters and subjects for Classes 6-12 at ₹999/month with a 3-day free trial, so you can resolve Chapter 3 doubts anytime, even at midnight during revision.

What is the most common mistake students make in ionic bonding questions?+

Students often forget to show the charges on ions after electron transfer. For example, in NaCl formation, you must write Na → Na⁺ + e⁻ (sodium loses one electron) and Cl + e⁻ → Cl⁻ (chlorine gains one electron), then show the electrostatic attraction between Na⁺ and Cl⁻. Omitting the + and − symbols costs marks even if the electron-dot diagram is correct.

Is it necessary to learn the thermite reaction for the board exam?+

Yes. The thermite reaction (Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat) is a classic example of displacement based on reactivity series and is used in welding railway tracks. It appeared in CBSE papers in 2019 and 2022, and tests both reactivity concepts and real-life applications. Memorise the equation and the practical use.

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