Pre Assessment | CBSE | G8 | Sound

Which of the following is true about sound?

• The number of oscillations per second of a vibrating object is called its time period

• Unwanted sound is called music

• Sound can travel through gases only

• Sound cannot travel in vacuum

Voice of which of the following is likely to have minimum frequency?

• Baby girl

• Baby boy

• A man

• A woman

In the following statements, tick ‘T’ against those which are true, and ‘F’ against those which are false.

• Unwanted or unpleasant sound is termed as music

• Sound cannot travel in vacuum

• The number of oscillations per second of a vibrating object is called its time period

• Noise pollution may cause partial hearing impairment

• If the amplitude of vibration is large, sound is feeble

A pendulum oscillates 40 times in 4 seconds. Find its time period and frequency.

• 0.1 seconds and 40 Hz

• 0.1 seconds and 4 Hz

• 0.4 seconds and 40 Hz

• 0.4 seconds and 10 Hz

Identify the sources of noise pollution in your locality.

• Construction work

• Musical instruments

• Television at low volume

• Plantation on the roadside

In what way noise pollution is harmful to humans.

• Causes relaxation

• Improves concentration

• Leads to hypertension and anxiety

• Enhances hearing abilities

Your parents are going to buy a house. They have been offered one on the roadside and another three lanes away from the roadside. Which house would you suggest your parents should buy?

• None of the above

• House on the roadside

• House three lanes away from the roadside

• Either house is fine

What is reflection of sound ?

• Repetition of the original sound heard after the sound is reflected.

• When sound waves hit a barrier or an obstacle they get reflected.

• None of these

• Both A and B

What is the unit of frequency?

• Second (s)

• Hertz (Hz)

• Decibel (dB)

• Metre (m)

What is the difference between noise and music?

• Noise is produced by musical instruments, music is not

• Noise is always loud, music is always soft

• Noise is unpleasant, music is pleasing

• Noise is always high-pitched, music is always low-pitched