Infra,Ultra and Audible Sound

Q. Which of the following animals are capable of hearing ultrasound?

1. Dog
2. Giraffe
3. Dolphin
4. Elephant

Q. What is the possible audible range in which old age people could hear?

1. 20 Hz - 25 kHz
2. 20 Hz - 20 kHz
3. 20 Hz - 12 kHz
4. 20 Hz - 30 kHz

Q.

What is the audible range of a normal human ear?

Q. The graph given here shows the frequency of sound emitted by a source for 30 seconds. For how many seconds a normal human being be able to hear the sound?

Time second \( \longrightarrow \)

1. 30 s
2. 25 s
3. 20 s
4. 10 s