Sound Part 1: MCQs (Q1–Q25)
🎵 Sound – Class 9 Science MCQs
Section 1: Nature of Sound, Production & Propagation of Sound Waves (Q1–Q25)
Q1. Sound is produced due to:
A. Flow of current
B. Vibrations of objects
C. Chemical reaction
D. Heating
✅ Correct Answer: B. Vibrations of objects
Explanation:
- A. Wrong, current produces electrical effects, not sound directly.
- B. Correct, vibrating bodies produce sound.
- C. Reactions may produce sound but only due to vibrations.
- D. Heating does not always produce sound.
Q2. Sound requires a ______ for its propagation.
A. Medium
B. Vacuum
C. High temperature
D. None
✅ Correct Answer: A. Medium
Explanation:
- Sound is a mechanical wave and needs medium (solid, liquid, or gas).
Q3. Which type of wave is sound in air?
A. Transverse
B. Longitudinal
C. Electromagnetic
D. Both A & B
✅ Correct Answer: B. Longitudinal
Explanation:
- Sound in air propagates via compressions and rarefactions → longitudinal.
Q4. Sound cannot travel in:
A. Solids
B. Liquids
C. Gases
D. Vacuum
✅ Correct Answer: D. Vacuum
Q5. Speed of sound is maximum in:
A. Air
B. Water
C. Steel
D. Vacuum
✅ Correct Answer: C. Steel
Explanation:
- Speed ∝ density and elasticity. Highest in solids, lowest in gases.
Q6. Compressions and rarefactions in air are regions of:
A. Low & high temperature
B. High & low pressure
C. High & low light
D. Magnetic field
✅ Correct Answer: B. High & low pressure
Q7. Frequency of audible sound for humans lies between:
A. 1–100 Hz
B. 20–20000 Hz
C. 20000–50000 Hz
D. > 50000 Hz
✅ Correct Answer: B. 20–20000 Hz
Q8. Sound of frequency below 20 Hz is called:
A. Ultrasonic
B. Infrasonic
C. Audible
D. Radio waves
✅ Correct Answer: B. Infrasonic
Q9. Sound of frequency above 20 kHz is called:
A. Subsonic
B. Supersonic
C. Ultrasonic
D. Megasonic
✅ Correct Answer: C. Ultrasonic
Q10. Which animal uses ultrasound for navigation?
A. Dogs
B. Cats
C. Bats
D. Humans
✅ Correct Answer: C. Bats
Q11. SI unit of frequency is:
A. Hertz
B. Newton
C. Joule
D. Watt
✅ Correct Answer: A. Hertz
Q12. SI unit of wavelength is:
A. m/s
B. m
C. Hz
D. J
✅ Correct Answer: B. m
Q13. Speed of sound in air at room temperature is approximately:
A. 150 m/s
B. 200 m/s
C. 330 m/s
D. 500 m/s
✅ Correct Answer: C. 330 m/s
Q14. Sound travels fastest in:
A. Vacuum
B. Air
C. Water
D. Steel
✅ Correct Answer: D. Steel
Q15. Wave speed formula is:
A. v = f/λ
B. v = f × λ
C. v = λ/f
D. v = f²λ
✅ Correct Answer: B. v = f × λ
Q16. If frequency of wave = 200 Hz and wavelength = 1.5 m, speed = ?
A. 200 m/s
B. 250 m/s
C. 300 m/s
D. 350 m/s
✅ Correct Answer: C. 300 m/s
Explanation:
- v = fλ = 200 × 1.5 = 300 m/s.
Q17. The time period of sound wave is reciprocal of:
A. Speed
B. Wavelength
C. Frequency
D. Amplitude
✅ Correct Answer: C. Frequency
Q18. Which of these has highest speed of sound?
A. Oxygen
B. Water
C. Copper
D. Vacuum
✅ Correct Answer: C. Copper
Q19. Sound is a form of:
A. Mechanical energy
B. Chemical energy
C. Electrical energy
D. Thermal energy
✅ Correct Answer: A. Mechanical energy
Q20. Sound travels in solids as:
A. Longitudinal only
B. Transverse only
C. Both longitudinal and transverse
D. Not at all
✅ Correct Answer: C. Both longitudinal and transverse
Q21. Amplitude of sound wave is related to:
A. Loudness
B. Pitch
C. Quality
D. Speed
✅ Correct Answer: A. Loudness
Q22. Frequency of sound wave is related to:
A. Loudness
B. Pitch
C. Quality
D. Speed
✅ Correct Answer: B. Pitch
Q23. Quality of sound depends on:
A. Amplitude
B. Frequency
C. Waveform
D. Wavelength
✅ Correct Answer: C. Waveform
Q24. When sound wave travels through air, particles of medium:
A. Move with wave
B. Oscillate about mean position
C. Travel forward continuously
D. Become stationary
✅ Correct Answer: B. Oscillate about mean position
Q25. Which property of sound helps us to identify a person by his voice?
A. Amplitude
B. Frequency
C. Quality (Timbre)
D. Wavelength
✅ Correct Answer: C. Quality (Timbre)
Sound Class 9 Science, CBSE Class 9 Science MCQs, NCERT Class 9 sound questions, Class 9 Science exam practice, Online learning Science Class 9, sound class 9 science mcqs with answers, cbse class 9 science sound multiple choice questions, ncert class 9 sound quiz online, important mcqs for cbse class 9 science sound chapter, sound class 9 mcqs for online learning