MCQ (Solution) - Sound | Science Class 8 PDF Download

Q1: What is the primary cause of sound production?
(a)  Heat
(b) Light
(c) Vibration
(d) Electricity

Correct Answer is Option (c)
The primary cause of sound production is the vibration of an object. Sound is a mechanical wave that travels through a medium, such as air, water, or solids. When an object vibrates, it disturbs the particles in the surrounding medium, creating compressions and rarefactions. These pressure variations propagate as waves, and our ears detect them as sound. Vibration of Air Particles

Q2: What is the role of the larynx in sound production by humans? 
(a) Filtering sound 
(b)  Controlling amplitude 
(c)  Producing vibrations 
(d) Enhancing pitch 

Correct Answer is Option (c)
 the larynx is a crucial anatomical structure involved in the production of sound by controlling the vibration and amplitude of the vocal cords, which is essential for generating speech, singing, and other vocalizations. Larynx

Q3: In which medium does sound travel the fastest? 
(a)  Solids 
(b) Liquids 
(c) Gases 
(d) Vacuum 

Correct Answer is Option (a)
Sound travels fastest through solids, as the particles in a solid are closely packed, allowing for efficient transmission of mechanical waves. The speed of sound in liquids is slower than in solids but faster than in gases. In gases, sound travels slowest due to the more spread-out and less rigid nature of gas particles. The specific speed of sound in any medium depends on factors like temperature, pressure, and density. Generally, warmer temperatures and denser mediums contribute to higher speeds of sound. Solid Iron

Q4: What characteristic determines the loudness of a sound wave? 
(a) Amplitude 
(b) Frequency 
(c) Time period 
(d)  Propagation speed 

Correct Answer is Option (a)
The characteristic that determines the loudness of a sound wave is its amplitude. Amplitude refers to the maximum displacement or distance that a particle in the medium (such as air, water, or a solid material) moves from its equilibrium position when a sound wave passes through it. In simpler terms, amplitude represents the intensity or strength of the sound wave. 

Q5: What is the unit of frequency? 
(a) Watts 
(b) Hertz 
(c) Decibels 
(d) Newton 

Correct Answer is Option (b)
The unit of frequency is the hertz (Hz). One hertz is defined as one cycle per second. It is named after the German physicist Heinrich Hertz, who made significant contributions to the study of electromagnetism and the understanding of waves. Therefore, when we measure the frequency of a sound wave or any periodic phenomenon, we express it in hertz. For example, if a sound wave completes 100 cycles in one second, its frequency is 100 hertz. 

Q6:What is the range of audible sound for humans? 
(a)  5 Hz to 50,000 Hz 
(b) 10 Hz to 100,000 Hz 
(c) 20 Hz to 20,000 Hz 
(d) 15 Hz to 30,000 Hz 

Correct Answer is Option (c)
The range of audible sound for humans typically falls between 20 hertz (Hz) and 20,000 Hz. This range is often referred to as the audible frequency range or the audio spectrum. The lower limit of 20 Hz represents the lower threshold of human hearing, while the upper limit of 20,000 Hz represents the higher threshold. 

Q7: What is the primary difference between noise and music? 
(a)  Frequency 
(b) Amplitude 
(c) Pattern and rhythm 
(d) Source of origin 

Correct Answer is Option (c)
The primary difference between noise and music lies in the organization of sound (Pattern and Rhythm). Music is organized sound with elements such as melody, harmony, rhythm, and often a deliberate structure, created for artistic or aesthetic purposes. In contrast, noise typically refers to random, chaotic, or disorganized sound without a specific pattern or intentional structure. 

Q8: What health problems can be caused by noise pollution? 
(a) Improved sleep 
(b) Enhanced concentration 
(c) Hypertension 
(d)  Increased hearing ability 

Correct Answer is Option (c)
Noise pollution has been associated with an increased risk of hypertension, and several mechanisms may contribute to this relationship. Prolonged exposure to high levels of noise can activate the body's stress response, leading to physiological changes that may contribute to hypertension. Hypertension Disorder

Q9: How can noise pollution be controlled? 
(a) Increasing volume 
(b) Planting trees 
(c) Using loudspeakers 
(d)  Ignoring awareness campaigns 

Correct Answer is Option (b)
Planting trees can control noise pollution because trees, with their leaves, branches, and trunks, can absorb and block sound waves. The soft surfaces of leaves and the porous nature of bark help to dissipate and absorb sound energy, especially at higher frequencies. This absorption can reduce the overall noise level in the surrounding area. Plantation

Q10: What does the amplitude of a sound wave determine? 
(a)  Loudness 
(b) Frequency 
(c) Time period 
(d) Propagation speed 

Correct Answer is Option (a)
The amplitude of a sound wave determines the loudness or volume of the sound. Amplitude refers to the maximum displacement or distance that a particle in the medium (such as air, water, or a solid material) moves from its equilibrium position when a sound wave passes through it.