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Important Questions: CBSE Class 8 Science Chapter 10 Sound

Sound is a high-yield chapter in the CBSE Class 8 Science syllabus, consistently appearing in both objective and subjective sections of the annual exam. Students must master the production and propagation mechanisms, understand the relationship between frequency, amplitude and pitch, and be able to discuss noise pollution with concrete examples. This question bank mirrors actual CBSE exam patterns from 2023-2025 and provides model answers to build confidence before the board or school term tests.

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Key takeaways

✓Chapter 10 Sound typically carries 5-8 marks in the CBSE Class 8 Science annual exam, appearing as MCQs, short answers and one long question.
✓Production and propagation of sound, characteristics like frequency and amplitude, and noise pollution form the three core sections tested every year.
✓MCQs often ask definitions of pitch, audible range and ultrasound; 2-mark questions test vibration examples and sound medium requirements.
✓3-mark questions include numerical problems on frequency-time period relationships and diagram-based answers on the human ear or sound wave characteristics.
✓5-mark questions usually combine noise pollution control measures with real-life case studies or data interpretation from traffic noise surveys.
✓Common mistakes include confusing frequency with amplitude, writing incorrect SI units for frequency (Hertz vs Hz), and incomplete labelling of ear diagrams.
✓CBSETUTOR.ai offers unlimited doubt solving for Sound and all Class 8 chapters at ₹999/month with a 3-day free trial—upload photo of any question for step-by-step solutions.

Chapter Overview and Marks Weightage

Chapter 10 Sound appears in the Physics section of CBSE Class 8 Science and typically carries 5 to 8 marks in the annual examination. The chapter builds on students' everyday experience with sound and formalises concepts like vibration, wave propagation through different media, frequency, amplitude, pitch, loudness, and the serious issue of noise pollution. In the 2024-25 session most CBSE schools allocated one 1-mark MCQ, one or two 2-mark short-answer questions, one 3-mark question (often numerical or diagram-based), and occasionally a 5-mark long answer or case study on noise pollution. Understanding the terminologies from NCERT—production and propagation, frequency and amplitude, pitch, audible and inaudible ranges, and noise pollution—is essential because exam questions quote these exact phrases.

Expected weightage: 5–8 marks out of 80 in the annual exam
Question types: 1 MCQ (1 mark), 1–2 VSA/SA (2 marks each), 1 numerical or diagram (3 marks), 1 long answer or case study (5 marks)
Key NCERT topics: production and propagation, frequency-amplitude-pitch relationships, human ear structure, noise pollution sources and control
Practical link: Students are often asked to recall the bell-jar experiment or tuning-fork demonstrations from the lab

1-Mark Questions: MCQs and Very Short Answers

One-mark questions test recall of definitions, units and basic facts. CBSE frequently frames MCQs around audible range (20 Hz to 20,000 Hz), ultrasound, infrasound, the SI unit of frequency (hertz or Hz), and identification of vibrating parts in musical instruments. Very short answer (VSA) questions ask for one-word or one-sentence answers such as naming the characteristic of sound that determines pitch or stating whether sound can travel in vacuum. Students should memorise exact definitions and numerical ranges from NCERT to score full marks without negative marking in the MCQ section.

2-Mark Questions: Production, Propagation and Medium

Two-mark questions require short explanations—typically two to three sentences or two distinct points. CBSE examiners often ask students to explain why sound needs a material medium, describe the bell-jar experiment, list examples of vibrating objects that produce sound, or differentiate between longitudinal and transverse waves. To earn both marks students must write complete sentences with scientific vocabulary. For instance, stating 'sound is produced by vibration' earns one mark; adding 'when an object vibrates it sets the surrounding medium into vibration creating compressions and rarefactions' secures the second mark. Including a labelled diagram of the bell-jar setup or a tuning fork can also fetch the full two marks even if the written explanation is brief.

3-Mark Questions: Frequency, Amplitude, Pitch and Numerical Problems

Three-mark questions test deeper understanding and often include numerical calculations or diagram-based answers. Common topics are the relationship between frequency and time period (frequency = 1 / time period), distinguishing between pitch and loudness, explaining amplitude and its effect on loudness, and labelling parts of the human ear with their functions. For numerical problems students must write the formula, substitute values with correct units and show the final answer with unit. For diagram questions CBSE awards one mark for neatness, one for correct labels and one for brief functional descriptions. Practising NCERT in-text numericals and end-of-chapter exercises ensures familiarity with the expected format and significant figures.

3-Mark Questions: Wave Characteristics and Graphs

CBSE sometimes provides a graph of a sound wave (displacement vs time or pressure vs distance) and asks students to identify amplitude, wavelength or frequency, or to compare two waves. These questions carry three marks and require students to read the graph carefully, mark the relevant distances or heights and write the definitions. Another pattern is to ask students to sketch two waves—one with higher amplitude and the same frequency, or one with higher frequency and the same amplitude—and explain the difference in sound. Clear, labelled sketches earn method marks even if the explanation is brief. Students should use a pencil and ruler for neat wave diagrams.

5-Mark Questions: Noise Pollution—Sources, Effects and Control

Five-mark long-answer questions on noise pollution are common in CBSE Class 8 Science. Students are expected to define noise, list at least four sources (traffic, loudspeakers, construction machinery, firecrackers, airports), explain harmful effects on human health (hearing loss, stress, sleep disturbance, high blood pressure) and suggest practical control measures (plantation of trees, soundproof windows, regulation of loudspeaker use, industrial zoning, use of silencers). A well-structured answer with subheadings—Definition, Sources, Effects, Control Measures—scores full marks. Including real examples like 'honking zones near hospitals are banned' or 'airport authorities install noise barriers' adds authenticity and can earn bonus appreciation from the examiner.

5-Mark Case-Based and Data-Interpretation Questions

Starting from the 2023-24 session CBSE introduced case-based questions even in Class 8 Science. A typical case study presents a real-world scenario—for example a table showing noise levels (in decibels) at different locations in a city or a paragraph about ultrasound use in medical imaging—and asks four to five sub-questions (MCQs or VSAs) totalling five marks. Students must read the passage carefully, extract data and apply chapter concepts. For Sound the case might describe a traffic survey recording dB levels at a crossroad during peak and off-peak hours, then ask which time exceeds safe limits (above 85 dB), what measures the municipality can take and which characteristic of sound is measured in decibels (loudness). Practising sample papers from 2024 and 2025 helps students get used to this format.

How CBSE Frames Questions from Chapter 10 Sound

CBSE question-paper setters follow NCERT language closely and design questions that test conceptual clarity rather than rote memory. For Chapter 10 Sound examiners pick one or two definitions (pitch, amplitude, frequency), one example-based question (name the part of the ear that vibrates, or give two examples of sound-absorbing materials), one numerical from frequency-time period or speed of sound, one diagram (human ear or a wave sketch) and one application-based question (noise pollution, ultrasound uses). They avoid direct NCERT exercise questions in the final paper but use similar structures with changed numbers or contexts. Between 2023 and 2025 CBSE increased the share of assertion-reason MCQs and case studies, so students should practise both formats. The marking scheme awards partial marks for correct method even if the final answer is wrong, so always write formulae and units clearly.

Definitions and terminology: Expect one MCQ and one VSA on audible range, ultrasound, infrasound, pitch, loudness, quality.
Conceptual short answers: Why sound needs a medium, difference between pitch and loudness, how amplitude affects loudness.
Numerical problems: Frequency = 1/T; sometimes speed = distance/time if a context like echo or thunder-lightning is given.
Diagram-based: Human ear labelling (3 marks), wave sketches comparing amplitude or frequency (3 marks).
Application and analysis: Noise pollution sources-effects-control (5 marks), case study with data table (5 marks).

Common Mistakes Students Make and How to Avoid Them

Even well-prepared students lose marks in Sound due to small errors. The most frequent mistake is confusing frequency with amplitude: writing 'high amplitude means high pitch' costs marks because pitch depends on frequency, not amplitude. Another common error is incorrect or missing units—writing '50' instead of '50 Hz' in a numerical problem. In diagram questions students often forget to label all parts or draw untidy sketches; CBSE awards marks for neatness and correct arrow placement. When explaining noise pollution many students list sources but omit effects or control measures, losing three out of five marks. Finally, in case-based questions students sometimes answer from general knowledge without referring back to the data table or passage, which leads to wrong conclusions. Careful reading of the question, underlining keywords like 'define', 'calculate', 'list', 'explain' and writing in points rather than long paragraphs helps avoid these pitfalls.

**Frequency vs amplitude confusion:** Remember pitch = frequency; loudness = amplitude. Write this in your rough notes before answering.
**Missing units:** Always write Hz for frequency, dB for loudness, s for time period. Half-mark deductions add up.
**Incomplete diagrams:** Use a sharp pencil, ruler for straight lines and label every part with an arrow. Practise ear diagram at least three times before the exam.
**Skipping steps in numericals:** Write Given, Formula, Substitution, Answer even if the calculation is simple. You earn method marks.
**Generic answers on noise pollution:** Give specific examples—'Trees absorb sound' is better than 'Plant trees'; 'Silencers in vehicles' is better than 'Reduce noise'.
**Not reading case-study data carefully:** Underline numbers and keywords in the passage; refer back to the table for each sub-question.

Additional 2-Mark and 3-Mark Practice Questions

To build exam confidence students should solve a variety of question styles beyond the NCERT exercise. Below are additional practice questions that mirror CBSE patterns from recent years. Work through these under timed conditions—allocate two minutes per 2-mark question and three to four minutes per 3-mark question. Self-check your answers against the model solutions and note any concept gaps. If you find numerical problems challenging, revise the formula sheet and practise at least five similar sums. For diagram-based questions keep a blank sheet and redraw the human ear or wave graphs until you can reproduce them from memory with labels. Regular practice reduces silly mistakes and improves speed, which is critical in the 90-minute Science paper where you must also cover Physics, Chemistry and Biology chapters.

How CBSETUTOR.ai Helps You Master Sound Questions

Understanding concepts like frequency, amplitude and noise pollution is one thing; applying them correctly under exam pressure is another. CBSETUTOR.ai gives every CBSE student a personal AI tutor available 24×7 at a flat ₹999 per month for all classes 6 to 12. When you are stuck on a tricky numerical—say calculating time period from frequency or interpreting a wave graph—simply snap a photo of the question and upload it in the app. Within seconds you receive a step-by-step solution tailored to CBSE marking schemes, with formula explanations and unit checks. The AI tutor also points out common mistakes like confusing pitch with loudness or forgetting to label diagram parts. Beyond Chapter 10 Sound you can ask doubts from any Science, Maths or Social Science chapter, making it a complete study companion. Parents appreciate the transparent pricing—no hidden charges, no per-question fees—and the 3-day free trial lets your child test the platform risk-free before the monthly subscription begins. Thousands of students across India now rely on CBSETUTOR.ai to clarify NCERT concepts, practise important questions and build exam confidence from the comfort of home.

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Final Revision Checklist for Chapter 10 Sound

One week before your term exam or annual paper, use this checklist to ensure you have covered every scoring area in Chapter 10 Sound. Tick off each item only after you can explain it to a study partner or write a model answer without looking at notes. Focus extra time on numerical problems and diagram labelling because these carry guaranteed marks if you follow the method. Revise the NCERT in-text questions and end-of-chapter exercises at least twice; CBSE often adapts these with minor changes. On the day before the exam do not start new topics—instead solve one full mock test of 10 to 12 Sound questions under timed conditions, then check answers and note down any formula or definition you forgot. A calm, systematic revision always outperforms last-minute cramming and helps you walk into the exam hall confident that you can handle any question pattern on Sound.

**Definitions memorised:** Production and propagation of sound, frequency, amplitude, pitch, loudness, quality, audible/inaudible ranges, noise pollution.
**Formulae practised:** Frequency f = 1/T; speed v = distance/time (for echo problems).
**Diagram mastery:** Human ear with labels (pinna, ear canal, eardrum, ossicles, cochlea, auditory nerve); wave sketches showing amplitude and frequency differences.
**Numerical problems:** Solve at least 5 sums on frequency-time period; 2 sums on echo distance calculation.
**Noise pollution:** Write one 5-mark answer covering definition, four sources, four harmful effects, four control measures—time yourself to finish in 7-8 minutes.
**NCERT exercises:** Complete all in-text and end-of-chapter questions; cross-check answers with NCERT solutions PDF.
**Mock test:** Attempt one 15-mark question set (1+2+3+3+5+1 pattern) in 25 minutes; self-evaluate and fix mistakes.

Frequently asked questions

How many marks does Chapter 10 Sound carry in the CBSE Class 8 Science annual exam?+

Chapter 10 Sound typically carries 5 to 8 marks in the CBSE Class 8 Science annual exam. The distribution includes one 1-mark MCQ, one or two 2-mark short answers, one 3-mark question (numerical or diagram) and sometimes a 5-mark long answer or case study on noise pollution.

What are the most important numerical topics in this chapter?+

The most important numerical topics are the relationship between frequency and time period (f = 1/T) and echo-related distance calculations using speed of sound. Practise at least five problems on calculating frequency when time period is given and vice versa, ensuring you write the correct unit (Hz for frequency, seconds for time period).

How should I prepare the human ear diagram for the exam?+

Draw the human ear diagram at least three times before the exam. Label the pinna, ear canal, eardrum (tympanic membrane), the three middle-ear bones (hammer, anvil, stirrup), cochlea and auditory nerve. Write one-line functions for the eardrum and cochlea. Use a pencil and ruler for neat lines; CBSE awards marks for clarity and correct labelling.

What is the difference between pitch and loudness?+

Pitch depends on the frequency of sound; a high-frequency sound has high pitch (shrill) and a low-frequency sound has low pitch (grave). Loudness depends on the amplitude of the sound wave; greater amplitude means louder sound. For example, a whistle has high pitch, while a drum beaten hard produces high loudness.

Which are common mistakes students make in Sound questions?+

Common mistakes include confusing frequency with amplitude (pitch vs loudness), forgetting to write units (Hz, dB, s), incomplete or untidy diagram labels, skipping steps in numerical problems, and giving generic answers on noise pollution without specific examples like 'silencers in vehicles' or 'tree plantation along highways'.

How do I score full marks in a 5-mark noise pollution question?+

Structure your answer with subheadings: Definition (1 mark), Sources—list at least four (1 mark), Harmful Effects—list at least four (1.5 marks), Control Measures—list at least four (1.5 marks). Use specific examples like 'ban on loudspeakers near hospitals' or 'use of silencers in vehicles' to make your answer stand out.

What is the audible range for humans and why is it important?+

The audible range for the average human ear is 20 Hz to 20,000 Hz. Sounds below 20 Hz are called infrasound and above 20,000 Hz are called ultrasound; both are inaudible to humans. This concept appears frequently in 1-mark MCQs and is used in case studies on ultrasound applications in medicine and industry.

Can sound travel through vacuum, and how is this tested in exams?+

No, sound cannot travel through vacuum because it is a mechanical wave that requires a material medium (solid, liquid or gas) to propagate. CBSE tests this concept through the bell-jar experiment description (2 marks) or as a 1-mark MCQ. Always mention 'sound needs particles to transmit compressions and rarefactions' in your answer.

How does CBSETUTOR.ai help with Sound chapter doubts?+

CBSETUTOR.ai offers 24×7 AI-powered doubt solving at ₹999/month for all classes 6-12. Upload a photo of any Sound question—numerical, diagram or theory—and receive step-by-step CBSE-aligned solutions within seconds. The platform explains common mistakes, checks units and provides worked examples, making it easier to master frequency-time period calculations, wave graphs and noise pollution answers. A 3-day free trial is available.

What are case-based questions on Sound and how to tackle them?+

Case-based questions present a real-world scenario or data table (for example, noise levels at different city locations) followed by four to five sub-questions totalling 5 marks. Read the passage carefully, underline key data points and refer back to the table for each sub-question. Practise sample papers from 2024-25 to get familiar with this format; CBSE introduced it to test application and analysis skills.

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