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