case /data -based (4 Marks)

Question 14 Marks

Aditi hangs four steel dishes of the same size but different thickness.
She hits each of them with an iron rod.

	Dish $1$	Dish $2$	Dish $3$	Dish $4$
Thickness of dish	$1\ mm$	$1.5\ mm$	$0.5\ mm$	$2\ mm$

$8.$ The thicker the dish, the lower will be the vibration.
Which dish will produce the loudest sound when hit$?$
$A.$ Dish $1$
$B.$ Dish $2$
$C.$ Dish $3$
$D. $ Dish $4$
$9.$ Which of these statements proves that sound can travel through solids$?$
$A.$ We can hear the sound of wind.
$B.$ We can hear the sound of lightning.
$C.$ We can hear a bell ringing from a distance.
$D.$ We can hear heartbeats by using a stethoscope.
$10.$ Which part of the human ear vibrates on receiving sound waves$?$
$A.$ Ear lobe
$B.$ Eardrum
$C.$ Inner ear
$D.$ Ear canal

Answer

$8. C.$ Dish $3$
$9. D.$ We can hear heartbeats by using a stethoscope.
$10. B. $ Eardrum

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Question 24 Marks

Which of these is true about the four sound waves$?$
Circle ‘Yes’ or ‘No’ to mark your responses.

Animal	Frequency range of sound waves
Elephant	$15–12000\ Hz$
Human	$20–22000\ Hz$
Dog	$65–45000\ Hz$
Chicken	$125–2000\ Hz$

$5.$ A cat made a purring sound that had a frequency of $35\ Hz.$
Which of the animals mentioned in the table can hear the purring$?$
$A.$ Only human
$B.$ Only elephant
$C.$ Dog and chicken
$D.$ Elephant and human
$6.$ Which of the following sounds can be classiied as noise for humans$?$
$A.$ Sounds that are softer than $20\ dB$
$B.$ Sounds that are in between $20\ dB$ and $40\ dB$
$C.$ Sounds that are between $40\ dB$ and $80\ dB$
$D.$ Sounds that are louder than $80\ dB$
$7.$ Which of these will reduce noise pollution?
Circle ‘Yes’ or ‘No’ to mark your responses.

Will this reduce noise pollution?	Yes or No
Regulating the use of loudspeakers	Yes/No
Setting up more thermal power plants	Yes/No
Using more electric vehicles	Yes/No

Answer

$5. D.$ Elephant and human
$6. D.$ Sounds that are louder than $80\ dB$
$7.$ Yes
No
Yes

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Question 34 Marks

Raghav kept a mini sound player in each of two similar containers.
He then tightly covered both the containers with stretched plastic sheets.
He placed some tiny rubber beads on the surface of the sheets.
The picture shows what Raghav noticed when he turned on the sound player.

$3.$ Which of these questions can be answered using the result of Raghav’s activity$?$
$A.$ Does sound travel as waves$?$
$B.$ Does sound produce vibration$?$
$C.$ Does sound travel through vacuum$?$
$D.$ Does sound travel faster in solids than in gases$?$
$4.$ Would the result of Raghav’s activity change if fewer beads had been used$?$ Explain your answer.

Answer

$3. B.$ Does sound produce vibration$?$
$4.$ Mentions that the result would remain the same as the vibration would still make the beads jump.

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Question 44 Marks

The picture shows four sound waves.

$1.$ Which sound wave has the highest pitch$?$
$2.$ Which of these is true about the four sound waves$?$
Circle ‘Yes’ or ‘No’ to mark your responses.

Is the statement true$?$	Yes or No
Wave $3$ is the loudest.	Yes/No
Wave $1$ and wave $4$ have nearly the same loudness.	Yes/No
Wave $2$ and wave $3$ have the same loudness.	Yes/No

Answer

$1.$ Mentions wave $2$ as the response
$2.$ Yes
Yes
No

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Science case /data -based (4 Marks)

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