Sound (ध्वनि) Ch(11) Practice Quiz in Hindi Part – 1 || Class 9 Science Practice Quizzes in English Posted on February 28, 2025February 28, 2025 by Anshul Gupta0% 0 votes, 0 avg 1 Sound (ध्वनि) Ch(11)Practice Quiz in Hindi Part – 1 || Class 9 Science Practice Quizzes in English 1 / 201. The speed of sound is: A. Dependent on the properties of the medium B. Constant in all media C. Always faster in solids than in liquids D. Not affected by temperature Explanation: The speed of sound is generally higher in denser materials. 2 / 202. Sound is produced by: A. Light waves B. Vibrating objects C. Stationary objects D. Heat energy Explanation: Vibrations create disturbances in the surrounding medium, which propagate as sound waves. 3 / 203. A stethoscope is used for: A. Amplifying sound waves B. Listening to sounds produced within the body C. Reducing reverberation D. Measuring the speed of sound Explanation: It uses multiple reflections to transmit the sound of the patient’s heartbeat to the doctor’s ears. 4 / 204. A region of high pressure in a sound wave is called: A. Rarefaction B. Compression C. Crest D. Trough Explanation: Compression is formed when the vibrating object pushes the air particles closer together. 5 / 205. When an object vibrates, it causes: A. The medium to remain stationary B. The speed of sound to decrease C. The particles of the medium to travel all the way to the listener D. The particles of the medium to vibrate in a chain reaction Explanation: The vibration of one particle causes the adjacent particles to vibrate, transmitting the sound wave. 6 / 206. The minimum distance of the obstacle from the source of sound for hearing a distinct echo is: A. 8.6 m B. 17.2 m C. Dependent on the speed of sound only D. 34.4 m Explanation: This distance is calculated based on the speed of sound in air and the time required to hear a distinct echo. 7 / 207. To hear a distinct echo, the time interval between the original sound and the reflected sound should be at least: A. 0.1 s B. 0.01 s C. 10 s D. 1 s Explanation: This is because the sensation of sound persists in our brain for about 0.1 s. 8 / 208. A region of low pressure in a sound wave is called: A. Crest B. Rarefaction C. Trough D. Compression Explanation: Rarefaction is formed when the vibrating object moves backward, creating more space between the air particles. 9 / 209. The time taken for one complete oscillation is called: A. Amplitude B. Time period C. Frequency D. Wavelength Explanation: Time period is measured in seconds. 10 / 2010. The speed of sound in air at 0°C is approximately: A. 5950 m/s B. 331 m/s C. 344 m/s D. 1531 m/s Explanation: The speed of sound in air increases with temperature. 11 / 2011. An echo is: A. The bending of sound waves B. The repetition of a sound due to reflection from a surface C. The persistence of sound due to repeated reflections D. The absorption of sound waves Explanation: An echo is heard when the reflected sound wave reaches the listener’s ear after the original sound wave has ended. 12 / 2012. The distance between two consecutive compressions or rarefactions is called: A. Wavelength B. Time period C. Amplitude D. Frequency Explanation: Wavelength is the distance over which the wave’s shape repeats. 13 / 2013. Megaphones and horns are designed to: A. Spread sound in all directions B. Send sound in a particular direction C. Increase the frequency of sound D. Reduce the speed of sound Explanation: They use multiple reflections to focus the sound waves. 14 / 2014. The reflection of sound follows: A. No specific laws B. Different laws than light reflection C. Only the law of refraction D. The same laws as light reflection Explanation: The angle of incidence equals the angle of reflection, and the incident sound wave, reflected sound wave, and the normal to the surface all lie in the same plane. 15 / 2015. Sound is a form of: A. Potential energy B. Light energy C. Kinetic energy D. Mechanical energy Explanation: Sound is produced by vibrations, which involve the movement of particles. This movement is a form of mechanical energy. 16 / 2016. Reverberation is: A. The absorption of sound waves B. The bending of sound waves C. The repetition of a sound due to reflection from a surface D. The persistence of sound due to repeated reflections Explanation: Reverberation can be reduced by using sound-absorbing materials on the walls and ceilings of a room. 17 / 2017. The law of conservation of energy states that: A. Energy can be destroyed B. Energy can be created C. Energy cannot be created or destroyed, only transformed D. Energy is always constant Explanation: The law of conservation of energy states that energy cannot be created or destroyed, but it can be converted from one form to another. 18 / 2018. The number of oscillations per unit time is called: A. Wavelength B. Time period C. Frequency D. Amplitude Explanation: Frequency is measured in Hertz (Hz). 19 / 2019. Sound waves are characterized by: A. The motion of particles perpendicular to the direction of wave propagation B. The motion of particles parallel to the direction of wave propagation C. The transfer of particles through the medium D. The absence of particle motion Explanation: This type of wave is called a longitudinal wave. 20 / 2020. The substance through which sound is transmitted is called a: A. Conductor B. Vacuum C. Insulator D. Medium Explanation: A medium can be a solid, liquid, or gas. Sound cannot travel through a vacuum. 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