Class 9 Science — Chapter 9: Sound
90 practice questions · 30 Easy · 30 Medium · 30 Hard
Practise Class 9 Science Chapter 9, "Sound", with 90 NCERT-aligned multiple-choice questions. The set is split into 30 Easy, 30 Medium and 30 Hard questions, so you can warm up on the fundamentals and then push into the exam-level problems that separate top scorers in CBSE Board exams and the JEE & NEET foundation years.
"Sound" is one of the chapters where concept clarity across physics, chemistry and biology basics really pays off. Each MCQ on this chapter is timed and uses exam-grade marking (+2 correct, −1 wrong, 0 skipped), training the same accuracy-under-pressure that real papers demand. Every question carries a short explanation, so a wrong answer becomes a quick lesson rather than a dead end — the fastest way to close gaps before a test.
Use this chapter as targeted revision: attempt the Easy set first to confirm your basics on Sound, then move to Medium and Hard to test application and problem-solving. Your accuracy, streaks and XP save automatically, and the chapter feeds into your overall Class 9 Science mastery score. A few sample questions are shown below; sign in free to practise all 90.
Key concepts: Sound (Class 9 Science)
This chapter covers the universal law of gravitation, free fall and the value of g, then mass and weight, and the related ideas of thrust, pressure, buoyancy and Archimedes' principle.
- Universal law of gravitation
- Every body attracts every other with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.
- Free fall and g
- An object falling under gravity alone is in free fall; its acceleration g ≈ 9.8 m/s² is independent of the object's mass.
- Mass vs weight
- Mass is the amount of matter (constant, in kg); weight is the gravitational force on it (W = mg, in newtons) and varies with g.
- Thrust and pressure
- Thrust is the force acting perpendicular to a surface; pressure is thrust per unit area, so a smaller area gives greater pressure.
- Buoyancy
- The upward force a fluid exerts on an immersed object; whether an object floats or sinks depends on its density relative to the fluid.
- Archimedes' principle
- An object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid it displaces.
Key formulas — Sound
💡 Exam tips for Sound
- g does not depend on the mass of the falling object — a heavy and a light body fall at the same rate (ignoring air).
- Mass stays the same everywhere; weight changes with g (e.g. it is about 1/6 on the Moon).
Sample questions
Sound waves cannot travel through:
Sound needs a medium (solid/liquid/gas). It cannot travel through vacuum.
SONAR uses:
SONAR (Sound Navigation And Ranging) sends ultrasonic pulses underwater.
Wavelength of a sound wave with frequency 340 Hz in air (v = 340 m/s) is:
λ = v/f = 340/340 = 1 m.
Sound — FAQs
What are the key concepts in Class 9 Science Sound?+
This chapter covers the universal law of gravitation, free fall and the value of g, then mass and weight, and the related ideas of thrust, pressure, buoyancy and Archimedes' principle. Key ideas include Universal law of gravitation, Free fall and g, Mass vs weight, Thrust and pressure, Buoyancy.
What does Class 9 Science Chapter 9 (Sound) cover on XamBaaz?+
It covers 90 NCERT-aligned MCQs on "Sound" — 30 Easy, 30 Medium and 30 Hard — each with a timed quiz and an instant explanation, suitable for CBSE Board exams and the JEE & NEET foundation years.
Are these "Sound" questions free to practise?+
Yes — sign in with Google to practise "Sound" free. Full unlimited access is ₹999/year (limited-time launch price), with no per-chapter charges.
How should I revise "Sound" for the exam?+
Start with the Easy quiz to confirm your fundamentals, then attempt Medium and Hard for application-level practice. Review each explanation, retry the questions you miss, and track your accuracy on this chapter until it is consistently high.
Practise all 90 questions free
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