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