Echo in Class 9 Science : Practice MCQ Questions & Answers with Explanations

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1.

When is an echo heard?

A

When sound is absorbed

B

When the reflected sound reaches after 1/10th of a second

C

When the source of the sound is moving

D

When the sound is reflected

View Answer

Correct Answer: B — When the reflected sound reaches after 1/10th of a second

Explanation:

An echo is heard when reflected sound reaches the listener after a noticeable time gap.