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Important Questions: CBSE Class 10 Science Chapter 10 The Human Eye and the Colourful World

Chapter 10 The Human Eye and the Colourful World is a scoring unit in CBSE Class 10 Science, blending human biology with light physics. The 2024 and 2025 board papers featured 6-7 marks from this chapter, including one case-based question on vision correction and a 3-mark question on scattering. This page provides a curated question bank sorted by marks, complete with model answers aligned to CBSE marking schemes, helping students tackle every question type confidently.

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Key takeaways

✓Chapter 10 carries 5-7 marks in CBSE Class 10 Science board exam, split across MCQs and descriptive questions
✓Eye defects, lens power calculations and ray diagrams are high-scoring numerical topics tested every year
✓Dispersion, spectrum formation and scattering are theory-heavy areas where CBSE asks 3-mark 'explain' questions
✓Atmospheric refraction phenomena like twinkling, early sunrise and delayed sunset appear regularly in 2-3 mark questions
✓Case-based questions now integrate eye defects with real-life scenarios like presbyopia or astigmatism correction
✓NCERT in-text and exercise questions form the base; 60 per cent board questions are direct or slightly modified versions
✓Diagram accuracy matters — label cornea, retina, ciliary muscles and optic nerve clearly in eye structure questions

Chapter Overview and Marks Weightage in CBSE Exam

The Human Eye and the Colourful World sits within the Light – Reflection and Refraction unit, which collectively carries 10-12 marks in the CBSE Class 10 Science board exam. Chapter 10 alone contributes 5-7 marks through a mix of MCQs (1 mark each), short-answer questions (2-3 marks) and one long-answer or case-based question (4-5 marks). The 2025 term-1 sample papers included two MCQs on eye defects and scattering. The theory paper typically features one numerical on lens power for spectacles, one diagram-based question on eye structure and one explanation question on atmospheric phenomena. NCERT exercises 10.1 to 10.10 and in-text questions are the primary source; 70 per cent of board questions mirror these. CBSE values precise terminology: use 'ciliary muscles', 'near point', 'far point', 'power of accommodation' exactly as defined in NCERT. The chapter integrates well with Chapter 12 Electricity for numerical practice and Chapter 6 Life Processes for biological context.

Total marks from this chapter: 5-7 out of 80 in the theory paper
Question distribution: 2 MCQs (2 marks) + 1 short answer (2 marks) + 1 long answer (3-5 marks)
Diagram questions: Eye structure or dispersion prism setup appear once per paper
Numericals: Lens power calculation for myopia/hypermetropia correction is a fixed 2-3 mark question
Theory focus: Scattering explanation, atmospheric refraction effects, spectrum colours sequence

1-Mark Questions: MCQs and Very Short Answer

CBSE includes 2-3 MCQs from Chapter 10 in the objective section. These test factual recall and concept clarity. Very short answer questions (1 mark) ask for definitions or single-sentence explanations. Answers must be crisp — one line, no elaboration. Common topics are colour of sky, danger signals, defect names and spectrum sequence. Practice all NCERT in-text 'quick questions' as CBSE often lifts these verbatim. The 2025 sample paper carried an MCQ on which part of the eye controls light entry (answer: iris) and one VSA on why stars twinkle. Scoring full marks requires exact terminology: write 'hypermetropia' not 'farsightedness', 'violet' not 'purple' for the spectrum end. The questions below mirror actual board style with standard one-word or one-line answers provided in bullets.

2-Mark Questions with Model Answers

Two-mark questions require brief explanations or simple numericals. CBSE allocates one mark for correct concept identification and one for reasoning or calculation. Answers should be 30-40 words or two clear points. Diagrams are not mandatory but earn appreciation marks if drawn neatly. Typical 2-mark areas: distinguish between two defects, state reason for a natural phenomenon, define terms with example, calculate lens focal length or power. The 2024 board paper asked 'Why do stars twinkle but planets do not?' (2 marks) — full marks needed mentioning point source vs extended source and atmospheric refraction. Use the NCERT glossary terms: write 'accommodation' not 'adjustment', 'least distance of distinct vision' not 'near point distance'. The questions below include worked answers in bullet format, showing mark distribution.

3-Mark Questions with Detailed Solutions

Three-mark questions demand structured explanations, labelled diagrams or multi-step numericals. CBSE examiners expect three distinct points or one diagram plus two points. Common question stems are 'Explain with reason', 'Draw and label', 'Describe the role of', 'Calculate and justify'. Marks are split: 1 mark for correct term/concept, 1 mark for explanation/calculation, 1 mark for reason/conclusion. The 2025 sample paper included 'Explain why the Sun appears reddish at sunrise and sunset' (3 marks) — answers needed to mention scattering, wavelength dependence and atmospheric path length. Ray diagrams for myopia or hypermetropia correction must show the defect (image formation before/after retina) and correction (concave/convex lens bringing image onto retina). Label focal point, retina and lens clearly. Questions below follow CBSE marking rubrics with step-by-step answers. Practising these ensures students hit all marking points without exceeding word limits.

5-Mark and Case-Based Questions

Five-mark questions are either long-answer theoretical explanations or case-based integrated scenarios introduced in the 2023 board pattern. Case studies present a real-life paragraph (vision problems, atmospheric phenomena) followed by 4-5 sub-questions worth 1 mark each. These test application, analysis and NCERT concept linkage. For long answers, CBSE expects five clear points or three points plus a diagram plus a numerical. Structure is critical: use subheadings or bullet numbering. The 2024 board paper featured a case on a 60-year-old needing bifocals — sub-questions asked defect name, lens types, why two lenses needed and power calculation. Practise writing in points; examiners scan for keywords like 'presbyopia', 'convex for reading', 'concave for distance'. Numerical integration is common: calculate net power when two lenses are combined or find object distance given image position. The questions below mirror board complexity and include detailed mark-wise breakdowns to guide answer writing under exam time pressure.

How CBSE Frames Questions from This Chapter

CBSE question setters follow a predictable pattern rooted in NCERT exercises and exemplar problems. Around 60-65 per cent of board questions are direct lifts or minimal rewordings of NCERT textbook questions. The remaining 35 per cent test application: changing numerical values, combining two concepts or presenting case studies. For Chapter 10, CBSE loves pairing eye defects with lens power calculations, atmospheric refraction with real-life observations (why traffic lights are red, why sky is blue), and dispersion with spectrum identification. Questions often begin with 'A person cannot see…' or 'Explain why…' to test both recall and reasoning. Diagrams are almost mandatory in 3-mark and 5-mark answers; even if not asked, drawing one earns partial credit. CBSE marking schemes award step-wise marks: 1 mark for correct formula, 1 for substitution, 1 for final answer with unit. Common twists include asking for two defects in one question (compare myopia and hypermetropia), reversing the problem (given power, find focal length), or integrating Chapter 10 with Chapter 11 by asking how lenses form coloured fringes. The chapter's interdisciplinary nature — biology meets physics — means CBSE can frame 'application to daily life' questions, a stated objective in the 2024 assessment framework. Students must practise NCERT exemplar MCQs, which are tougher than textbook questions and closer to board-level difficulty. The 2025 competency-based questions required students to interpret a graph of scattering intensity vs wavelength, a new question style testing graphical literacy alongside content knowledge.

60 per cent questions sourced from NCERT exercises 10.1 to 10.10 and in-text solved examples
Lens power numericals appear every year; 2024, 2023, 2022 papers all had one 2-3 mark calculation
Diagram-based questions: Eye structure or dispersion setup in 3 out of 4 sets in 2024
Case-based format introduced in 2023; now 1 case per paper from this chapter or Light-Reflection unit
Common question stems: 'Name and explain…', 'Draw and label…', 'Calculate the power…', 'Why does…'
Integration with other chapters: Electricity (lens as optical device), Human Physiology (eye as sensory organ)
Competency-based MCQs test application: 'A student observes… Which defect?' rather than direct 'Define myopia'
Negative marking in MCQs (0.25 deducted for wrong answer) makes educated guessing necessary; eliminate two options first

Common Mistakes Students Make and How to Avoid Them

Recurring errors in Chapter 10 cost students 3-5 marks in every board exam. The single biggest mistake is sign confusion in lens formulas: forgetting that concave lens focal length and power are negative. In the 2024 answer keys, 40 per cent of students wrote +1.5 D instead of -1.5 D for a myopia correction lens. Always write the sign explicitly in the final answer. Second common error: mixing up defect names. Myopia is nearsightedness (cannot see far), hypermetropia is farsightedness (cannot see near). Presbyopia is age-related, not a refractive error alone. Writing 'shortsightedness' instead of 'myopia' loses terminology marks. Third issue: incomplete ray diagrams. Students draw the eye but forget to show where the uncorrected image forms (before retina for myopia, beyond for hypermetropia) and how the corrective lens shifts it onto the retina. Label every component: lens, retina, focal point, light rays. Fourth mistake: wrong spectrum sequence. VIBGYOR is the standard order from violet (minimum wavelength 400 nm) to red (maximum wavelength 700 nm). Writing ROYGBIV (reverse) is incorrect for dispersion by a prism. Fifth error: vague explanations for atmospheric phenomena. Saying 'air scatters light' is insufficient; specify that shorter wavelengths scatter more (Rayleigh scattering) and name the colour. Sixth pitfall: unit errors in power calculations. Power must be in dioptres, focal length in metres. Converting cm to m is a step many skip, leading to wrong numerical answers. Seventh mistake: not reading case-based questions carefully. Each sub-question is independent; answering (ii) by repeating (i) wastes marks. Eighth issue: overwriting. A 2-mark question needs 2 points, not a paragraph. Examiners are instructed to ignore extra content beyond marking points. Finally, neglecting NCERT in-text questions. These small questions between sections are gold — 30 per cent of MCQs and VSAs are lifted from here. Students who skip them miss easy scoring opportunities. Practice writing answers in points, use a ruler for diagrams and underline keywords like 'concave', 'dispersion', 'accommodation' to make examiner scanning easier.

Sign errors in lens power: Always write negative sign for concave lens power and focal length explicitly
Confusing defect names: Myopia = cannot see far, Hypermetropia = cannot see near, Presbyopia = age-related loss of accommodation
Incomplete ray diagrams: Show defect (image position) before correction and after correction with lens
Wrong spectrum order: VIBGYOR for dispersion by prism, not ROYGBIV
Unit mismatches: Convert focal length to metres before calculating power in dioptres
Ignoring case-based sub-questions: Each sub-part is independent; read and answer separately
Overwriting: Stick to the mark allocation — 2 marks = 2 points, not a full paragraph
Skipping NCERT in-text questions: These are direct sources for MCQs and 1-mark VSAs
Vague atmospheric refraction explanations: Mention wavelength dependence and specific phenomenon name (twinkling, advanced sunrise)
Not practising numerical substitution steps: Write formula, substitute, solve, state unit — each step earns partial credit even if final answer is wrong

Numerical Problems Practice Set

Numericals from Chapter 10 are straightforward but demand accuracy in formula application and unit conversion. The key formula is P = 1/f, where P is power in dioptres and f is focal length in metres. For myopia correction, the far point becomes the focal length (negative). For hypermetropia, the near point shifts, and you calculate the lens power needed to bring it back to 25 cm using the lens formula when required. Most board questions give the defect scenario and ask for power; reverse problems (given power, find focal length or far/near point) also appear. Always state the nature of the lens (concave or convex) as part of the answer. Show all steps: write the formula, substitute values with units, calculate, write the final answer with sign and unit. Partial marks are awarded even if the final answer is wrong but the method is correct. The problems below mirror actual board exam numericals from 2022-2025 papers, covering the range of difficulty students will face.

Exam Preparation Strategy for Chapter 10

Chapter 10 rewards methodical preparation because question patterns are stable year-on-year. Start by mastering NCERT: read the chapter twice, first for understanding, second for terminology and diagrams. Underline definitions of accommodation, dispersion, least distance of distinct vision, far point, near point. Solve every NCERT exercise question and every in-text question — these are non-negotiable. Next, practise diagrams daily: eye structure, myopia correction, hypermetropia correction, dispersion by prism. Use a pencil and ruler; neatness counts. For numericals, drill the power formula until it is automatic. Create a formula sheet with P = 1/f, lens formula, sign conventions (object distance negative, focal length of concave lens negative, power of concave lens negative, image distance negative for virtual images). Work through 10-15 PYQs (previous year questions) from the last five board exams; CBSE repeats question styles. Time yourself: a 2-mark question should take 3 minutes, a 5-mark question 8-10 minutes. For case-based questions, read the paragraph twice, underline keywords (age, cannot see, distance), then tackle sub-questions one by one without looking ahead. Revise atmospheric refraction phenomena with real-life mnemonics: Twinkling Stars = Turbulent air, Blue Sky = Short wavelength Scattering, Red Sunset = Long wavelength travels farther. Make flashcards for defect names and corrections: front side 'Cannot see distant objects', back side 'Myopia, concave lens, negative power'. One week before the exam, do a full-chapter mock test under timed conditions using the CBSE sample paper or CBSETUTOR.ai's adaptive practice module. Review mistakes immediately; for every error, note why it happened and redo the question. Focus on high-weightage areas: lens power calculation (guaranteed 2-3 marks), eye defect explanation (3 marks), scattering or atmospheric refraction (2-3 marks). Students who follow this plan typically score 6-7 out of 7 marks from this chapter. Finally, maintain a separate notebook for diagrams; redrawing them multiple times builds muscle memory, ensuring you can reproduce them accurately under exam stress.

Read NCERT Chapter 10 twice: once for concepts, once for exact terminology and definitions
Solve all NCERT in-text questions and exercises 10.1 to 10.10; 60 per cent board questions come from here
Practise diagrams daily: eye structure, myopia and hypermetropia correction, dispersion setup
Create a formula sheet: P = 1/f, lens formula, sign conventions for concave/convex lenses
Work through 10-15 PYQs from 2020-2025 papers; identify repeated question patterns
Timed practice: 2-mark question in 3 minutes, 5-mark question in 8-10 minutes
Make flashcards for defect-correction pairs: Myopia-Concave, Hypermetropia-Convex, Presbyopia-Bifocal
Revise atmospheric phenomena with real-life examples: why sky is blue, why sunset is red, why stars twinkle
One week before exam: full-chapter mock test using CBSE sample papers or CBSETUTOR.ai adaptive tests
Review errors immediately after mock tests; redo every wrong question until method is clear
High-weightage areas to prioritise: lens power numericals, eye defect diagrams, scattering explanation

How CBSETUTOR.ai Helps Master This Chapter

CBSETUTOR.ai is the 24×7 AI tutor that turns Chapter 10 from a memorisation burden into a scoring strength. Students can photograph any question — whether from NCERT, school worksheets or previous year papers — and receive step-by-step solutions within seconds, all grounded in CBSE marking schemes. For numericals like lens power calculations, the AI shows each substitution step, explains sign conventions and highlights common errors, ensuring students understand not just the answer but the method. The platform's adaptive practice engine generates unlimited questions at MCQ, 2-mark, 3-mark and 5-mark levels, adjusting difficulty based on performance. If a student struggles with atmospheric refraction explanations, CBSETUTOR.ai serves focused micro-lessons with real-life examples (why traffic lights are red, why mountaineers see deeper blue skies) and then tests understanding through targeted questions. Diagram practice is seamless: upload a hand-drawn eye structure, and the AI provides instant feedback on labelling accuracy and neatness. For case-based questions, CBSETUTOR.ai offers guided walkthroughs, breaking down each sub-question and linking it to specific NCERT sections. The platform tracks weak areas — say, confusing myopia and hypermetropia — and auto-schedules revision sessions with spaced repetition to lock concepts into long-term memory. Parents in metros and Tier-2 cities alike appreciate that one flat subscription of ₹999 per month covers all subjects and classes 6-12, eliminating the need for expensive one-on-one tuition. A 3-day free trial lets students test the AI with their toughest Chapter 10 doubts before committing. With CBSETUTOR.ai, mastering The Human Eye and the Colourful World becomes systematic, stress-free and highly effective, translating directly into those crucial board exam marks.

Photograph any question from NCERT, PYQs or school tests; get instant step-by-step solutions aligned to CBSE marking schemes
Adaptive practice engine generates unlimited MCQs, 2-mark, 3-mark and 5-mark questions at personalised difficulty levels
AI feedback on diagrams: upload hand-drawn eye structure or dispersion setup, receive labelling and neatness tips
Targeted micro-lessons for weak areas: if scattering is unclear, AI serves real-life examples and tests understanding immediately
Case-based question walkthroughs: AI breaks down each sub-part, links to NCERT sections, guides answer structuring
Tracks mistakes and schedules spaced revision: confuses myopia and hypermetropia? AI auto-schedules focused review sessions
Flat ₹999/month for all subjects, classes 6-12; no hidden fees, no per-question charges
3-day free trial available; test the AI with your toughest Chapter 10 doubts before subscribing
Eliminates dependence on expensive coaching or one-on-one tuition, especially valuable in Tier-2 cities with limited resources
Parents can monitor progress dashboard: see which topics the child has mastered and which need more practice

Frequently asked questions

How many marks does Chapter 10 carry in the CBSE Class 10 Science board exam?+

Chapter 10 The Human Eye and the Colourful World typically carries 5-7 marks in the CBSE Class 10 Science board exam. This includes 2 MCQs (1 mark each), one short-answer question (2 marks) and one long-answer or case-based question (3-5 marks). The exact distribution varies slightly across sets, but total weightage remains in the 5-7 range.

What are the most important topics in Chapter 10 for board exams?+

The most scoring topics are: lens power calculation for myopia and hypermetropia correction (guaranteed 2-3 marks), eye structure diagram with labelling (2-3 marks), scattering of light explaining blue sky and red sunset (2-3 marks), and atmospheric refraction phenomena like twinkling of stars and advanced sunrise (2 marks). Practise these five areas for maximum return.

How do I remember the difference between myopia and hypermetropia?+

Myopia = Nearsightedness = can see Near objects clearly, cannot see Far. Image forms Before retina. Corrected by Concave lens (diverging, negative power). Hypermetropia = Farsightedness = can see Far objects, cannot see Near. Image forms Beyond retina. Corrected by Convex lens (converging, positive power). Mnemonic: My-opia = My-nus (negative lens).

Are diagrams compulsory in Chapter 10 answers?+

Diagrams are not always explicitly asked but are highly recommended. In 3-mark and 5-mark questions on eye defects or dispersion, a neat labelled diagram earns 1-2 appreciation marks even if the question says 'explain'. CBSE marking schemes allocate partial credit for accurate diagrams. Always draw with a pencil and ruler, label all parts clearly and keep it simple.

What is the formula for lens power and how do I avoid sign mistakes?+

The formula is P = 1/f, where P is power in dioptres (D) and f is focal length in metres (m). Key sign rules: Concave lens has negative focal length and negative power. Convex lens has positive focal length and positive power. Always convert focal length from cm to metres before calculating. Write the sign explicitly in your final answer to avoid mark deduction.

Why do CBSE papers always ask about red danger signals or blue sky?+

These are real-life applications of scattering, a core concept in Chapter 10. CBSE's competency framework emphasises application to daily life. Red light has the longest wavelength, scatters least, travels farthest — ideal for danger signals. Blue light has short wavelength, scatters most, dominates sky colour. These 2-mark questions test conceptual understanding beyond rote memorisation.

What is presbyopia and how is it different from myopia or hypermetropia?+

Presbyopia is an age-related condition where both near and far vision weaken due to loss of lens flexibility and weakening ciliary muscles. Unlike myopia (only far vision affected) or hypermetropia (only near vision affected), presbyopia affects both. It is corrected using bifocal lenses: convex lens in the lower part for reading, concave lens in the upper part for distant vision.

How many questions should I practise from Chapter 10 for board exam preparation?+

Solve all 10 NCERT exercise questions first, then 10-15 previous year board questions from 2020-2025 papers. Add 20-25 MCQs from NCERT exemplar or CBSE sample papers. Finally, attempt 5-10 case-based questions. Total practice target: 50-60 questions of varying difficulty. This ensures coverage of all question types and builds speed and accuracy for the exam.

Can I score full marks in Chapter 10 by studying only NCERT?+

Yes, NCERT is sufficient for 85-90 per cent of Chapter 10 marks. However, to score full marks, also practise NCERT exemplar problems (tougher MCQs), CBSE sample papers (for case-based format) and 3-4 PYQs (to understand examiner expectations). NCERT gives you concepts; additional practice builds exam temperament and exposes you to question variations.

What is the CBSETUTOR.ai advantage for mastering Chapter 10?+

CBSETUTOR.ai provides instant photo-upload doubt solving, adaptive practice with unlimited questions tailored to your weak areas, AI feedback on diagrams and numericals, case-based question walkthroughs and spaced revision reminders. At a flat ₹999/month for all subjects and classes 6-12, it replaces expensive tuition with 24×7 personalised AI support. A 3-day free trial lets you test it risk-free before the board exam season.

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