62 A 62 B 62 C 63 A 63 B 63 C 64 A 64 B 65 A 65 B 65 C 66 A 66 B 66 C 67 A 67 B 68

Lakhmir Singh & Manjit Kaur - Physics

Very Short Answer Type Questions-Pg-185

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Short Answer Type Questions-Pg-186

41 42 43 A 43 B 44 45 46 47 48 A 48 B 49 50 51 52 53 54 55 56 57 58 59 60 A 60 B 61 A 61 B 62 A 62 B 67 A 67 B

Long Answer Type Questions-Pg-187

63 A 63 B 64 A 64 B 65 A 65 B 66 A 66 B

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Questions Based on High Order Thinking Skills (HOTS)-Pg-188

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38 39 40 41 42 43 44 45 46 47 A 47 B 48 A 48 B 49 50 51 52 53 54 55 56 57 58 A 58 B 59 A 59 B 60 61

Long Answer Type Questions-Pg-208

62 A 62 B 62 C 63 A 63 B 63 C 64 A 64 B 65 A 65 B 65 C 66 A 66 B 66 C 67 A 67 B 68

Multiple Choice Questions (MCQs)-Pg-208

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Questions Based on High Order Thinking Skills (HOTS)-Pg-209

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Q. 63 A4.3( 12 Votes )

What is an echo?

Class 9th Lakhmir Singh & Manjit Kaur - Physics 5. Sound

Answer :

The repetition of sound wave caused by the reflection of sound wave is called echo. For an echo to happen it requires a hard surface like a tall brick wall or clif to bounce the sound back.

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