Practice exercise of class 8 science of Jawahar Navodaya Vidyalaya part 2
1. The range of human audibility lies between
a. 10 to 10000 Hz
b. 20 to 20000 Hz
c. 30 to 30000Hz
d. 40 to 40000000 Hz
answer b
2. Bat can know about their prey at a long distance even in the night by emitting
a. infra-red light
b. ultraviolet lights
c. chemical from their body
d. ultrasonic sounds
answer d
3. Which type of sound produced by a bat?
a. audible
b. subsonic
c. infrasonic
d. ultrasonic
answer d
4. Ultrasound cleaner use ultrasonic waves of frequency about................. .
a, 40 KHZ
b. 80 KHZ
c. 5 KHZ
d. 100 KHZ
answer a
5. The unit of noise pollution (level) is measured in
a. decibel
b. decimal
c. ppm
d. none of these
answer a
6. SONAR is a device to measure distance, direction and speed of underwater objects.
It is based on
a. light wave
b. infrasonic wave
c. ultrasonic wave
d. radio waves
answer c
7. The location of submerged objects can be detected by
a. Radar
b. SONAR
c. Quasar
d. Pulsar
answer b
8. The depth of oceans can be measured by
a. Radar
b. SONAR
c. Quasar
d. Pulsar
answer b
9. The study of behaviours of vibrating string can be detected by of sound.
a. sonometer
b. barometer
c. hydrometer
d. hygrometer
answer a
10. What is the name of the strings which vibrate in our voice box when we talk is
a. air column
b. pina
c. vocal cord
d. string
answer c
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