Sound – MCQs with Answers and Explanations
CBSE Class 8 Science – Chapter Wise Study Materials Based on NCERT
Chapter 13: Sound – Multiple Choice Questions (MCQs) with Answers & Explanations
Suitable for:
Annual Examination • Periodic Tests • Class Tests • Pre-Board / School Level Board Exam Pattern
These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 8 board exams standard.
This page contains a topic-wise set of 50 MCQs from Chapter 13: Sound. Each question is followed by the correct answer and an easy, concept-clearing explanation to support strong NCERT-based understanding and revision.
Topic-wise MCQs – Chapter 13: Sound
A. Basics of Sound and Vibrations
Q1.Sound is a form of:
Answer: (B)
Sound is a form of energy that produces the sensation of hearing in our ears. It is not matter or force, but energy carried by vibrations.
Q2.Sound is produced when:
Answer: (C)
Whenever an object vibrates (moves to and fro about its mean position), sound is produced. If there are no vibrations, no sound is produced.
Q3.The to-and-fro motion of a body about its mean position is called:
Answer: (C)
The back-and-forth motion about a fixed position is called vibration or oscillation. These vibrations produce sound.
Q4.Which of the following is NOT a vibrating source of sound?
Answer: (C)
Still water does not vibrate, so it does not produce sound. Guitar strings, drum membranes and vocal cords all produce sound when they vibrate.
Q5.Sound produced by humans is mainly due to vibrations of:
Answer: (B)
Humans produce sound when air from the lungs passes through and makes the vocal cords vibrate in the voice box (larynx).
Q6.The voice box is also known as the:
Answer: (C)
The voice box that contains the vocal cords is called the larynx. It is located in the throat region.
Q7.Children usually have:
Answer: (B)
Children have shorter, thinner vocal cords that vibrate faster, producing a shriller (higher pitch) voice compared to adults.
Q8.When vibrations of a sounding body stop, the sound produced:
Answer: (C)
Sound is directly linked to vibrations. If vibrations stop, sound also stops because no more energy is sent to the medium.
B. Propagation of Sound and Need for a Medium
Q9.The process by which sound travels from one place to another is called:
Answer: (C)
The term propagation of sound is used for the way sound waves travel from the source to the listener through a medium.
Q10.Sound cannot travel through:
Answer: (D)
Sound needs particles to carry vibrations. In vacuum there are no particles, so sound cannot travel through it.
Q11.Sound travels fastest in:
Answer: (C)
Particles are closest in solids like steel, so vibrations are passed on quickly and sound travels fastest in solids.
Q12.Which one of the following is a common medium for sound to reach our ears on Earth?
Answer: (A)
On Earth, most sounds we hear reach us through the air, which is the most common medium for sound propagation.
Q13.We cannot hear sound on the Moon because:
Answer: (C)
The Moon has almost no atmosphere, so there is no medium like air to carry sound waves, hence we cannot hear sounds there.
Q14.In the bell-jar experiment, the sound of the bell becomes fainter as air is pumped out because:
Answer: (B)
As air is removed, there are fewer particles to carry vibrations, so less sound energy reaches the ear and the sound becomes fainter.
Q15.Sound travels from a source to a listener by:
Answer: (B)
Sound is carried by the energy of vibrations, which is transferred from one particle of the medium to the next; particles themselves do not travel from source to listener.
C. Characteristics of Sound – Amplitude, Frequency, Loudness & Pitch
Q16.Amplitude of a vibration is:
Answer: (B)
Amplitude is the maximum distance of a vibrating particle from its mean position and is related to the energy of the sound.
Q17.Loudness of sound mainly depends on:
Answer: (A)
A sound with larger amplitude is louder. A smaller amplitude gives a softer sound, keeping other factors same.
Q18.The unit of frequency is:
Answer: (C)
Frequency is measured in hertz (Hz), which means number of vibrations per second.
Q19.Time taken to complete one vibration is called:
Answer: (C)
The time period is the time taken to complete one full vibration or oscillation.
Q20.If a vibrating body makes 200 vibrations in 4 seconds, its frequency is:
Answer: (B)
Frequency = number of vibrations ÷ time = 200 ÷ 4 = 50 Hz.
Q21.Which relation between frequency (f) and time period (T) is correct?
Answer: (B)
Frequency and time period are inversely related: f = 1/T and T = 1/f.
Q22.Pitch of sound depends on:
Answer: (B)
Pitch (shrillness or deepness) of a sound depends on its frequency. Higher frequency → higher pitch; lower frequency → lower pitch.
Q23.Which of the following sounds has the highest pitch?
Answer: (C)
A whistle produces a shrill sound of high frequency, so it has higher pitch than drum, roar, or thunder which are deeper sounds.
Q24.Two sounds have the same loudness but different pitches. Which statement is correct?
Answer: (B)
Same loudness → same amplitude; different pitch → different frequency. So amplitude is same, frequency differs.
Q25.Quality or timbre of a sound helps us to:
Answer: (B)
Quality/timbre allows us to identify whose voice it is or which instrument is playing, even if pitch and loudness are the same.
Q26.When a drum is beaten harder, the sound produced has:
Answer: (B)
Beating harder increases amplitude, so sound becomes louder. The frequency (and pitch) does not change much for the same drum, so pitch is almost same.
D. Audible Range, Infrasonic and Ultrasonic Sounds
Q27.The range of audible sound for a normal human ear is approximately:
Answer: (B)
A normal human ear hears sounds roughly between 20 Hz and 20 000 Hz. Below or above this range, sounds are inaudible to humans.
Q28.Sounds with frequency less than 20 Hz are called:
Answer: (C)
Frequencies below the audible range (< 20 Hz) are called infrasonic sounds.
Q29.Sounds with frequency greater than 20 000 Hz are called:
Answer: (A)
Frequencies above 20 000 Hz are called ultrasonic sounds. Humans cannot hear them, but some animals can.
Q30.Which of the following animals can hear ultrasonic sound?
Answer: (B)
Bats can hear and produce ultrasonic sounds, which they use for navigation and finding food in the dark.
Q31.Human beings cannot hear infrasonic and ultrasonic sounds because:
Answer: (B)
Human ears respond only to frequencies in the audible range. Infrasonic and ultrasonic sounds have frequencies outside this range, so we cannot hear them.
E. Music, Noise and Noise Pollution
Q32.Which of the following is an example of musical sound?
Answer: (C)
A flute produces a regular, pleasant and rhythmic sound, so it is musical. The others are harsh and irregular, so they are noise.
Q33.Noise can be defined as:
Answer: (B)
Noise is any unwanted, unpleasant and often loud sound that causes discomfort to our ears and mind.
Q34.Which of the following is NOT a source of noise pollution?
Answer: (B)
Soft, low-volume music is not noise and usually does not cause discomfort, while the others produce loud and disturbing sounds, causing noise pollution.
Q35.Noise pollution mainly refers to:
Answer: (B)
Noise pollution means presence of excessive, unwanted sound in the environment that can harm humans and animals.
Q36.Which of the following effects is NOT caused by noise pollution?
Answer: (C)
Noise pollution usually causes headache, lack of concentration, disturbed sleep and can lead to hearing loss, but it does not improve memory.
Q37.Long-term exposure to loud noise can lead to:
Answer: (B)
Loud noise for a long time can damage the delicate parts of the ear, causing partial or permanent hearing loss.
Q38.Which action will help in reducing noise pollution?
Answer: (C)
Trees act as natural sound barriers, absorbing and scattering sound, so planting more trees reduces noise pollution.
Q39.Silence zones should be created around:
Answer: (B)
Schools and hospitals need peaceful surroundings for study and patient recovery, so they are declared silence zones to control noise.
Q40.Which step can students take to reduce noise pollution?
Answer: (C)
Students can help by avoiding unnecessary horns and keeping volume low on TV and music systems. Loud crackers and loud music increase noise pollution.
F. Human Ear – Structure, Working and Care
Q41.The visible outer part of the ear is called:
Answer: (B)
The external flap-like part of the ear is called the pinna. It collects sound waves and directs them into the ear canal.
Q42.The eardrum is a:
Answer: (B)
The eardrum (tympanum) is a thin, tightly stretched membrane that vibrates when sound waves strike it.
Q43.Which part of the ear converts vibrations into electrical signals?
Answer: (C)
The cochlea in the inner ear has fluid and sensitive hair cells which convert vibrations into electrical signals for the brain.
Q44.The three small bones in the middle ear are:
Answer: (A)
The three bones of the middle ear are called hammer, anvil and stirrup. They amplify and transmit vibrations from eardrum to inner ear.
Q45.The nerve that carries sound information to the brain is:
Answer: (B)
The auditory nerve carries electrical signals from the cochlea to the brain, where they are interpreted as sound.
Q46.Which of the following is a good practice to protect our ears?
Answer: (C)
To protect hearing, we should avoid very noisy places, keep volume low, and never use sharp objects in the ear. Loud music and loudspeakers can damage ears.
Q47.Continuous ringing sound in the ear after loud noise is a sign of:
Answer: (C)
Ringing in the ear (tinnitus) after loud noise is a warning sign of possible damage to the inner ear and should not be ignored.
Q48.If there is pain or discharge from the ear, one should:
Answer: (C)
Ear pain or discharge may indicate infection or injury. We should consult a doctor early to prevent serious damage or hearing loss.
G. Mixed Conceptual & Application-Based MCQs
Q49.A girl hears an approaching train earlier by placing her ear on the track than by standing in air. This shows that:
Answer: (B)
The train’s sound reaches through the solid track earlier because sound travels faster in solids than in gases like air.
Q50.Two students are talking in a noisy traffic area. What should they do for better communication without shouting?
Answer: (C)
Moving to a quieter place or standing closer reduces the effect of background noise, making it easier to hear each other without shouting.
These 50 topic-wise MCQs with detailed explanations are prepared strictly according to the
NCERT Class 8 Science textbook for Chapter 13: Sound, and are ideal for self-study,
classroom practice and CBSE Class 8 board exam standard preparation.