A stone is dropped into a lake from a tower 500 metre high. The sound of the splash will be heard by the man approximately after 

[Given : Speed of sound = 340 m/s ]

1. 11.5 seconds

2. 21 seconds

3. 10 seconds

4. 14 seconds

When sound waves travel from air to water, which of the following remains constant 

1. Velocity

2. Frequency

3. Wavelength

4. All the above

At what temperature velocity of sound is double than that of at 0°C 

1. 819 K

2. 819°C

3. 600°C

4. 600 K

If velocity of sound in a gas is 360 m/s and the distance between a compression and the nearest rarefaction is 1m, then the frequency of sound is 

1. 90 Hz

2. 180 Hz

3. 360 Hz

4. 720 Hz

If the density of oxygen is 16 times that of hydrogen, what will be the ratio of their corresponding velocities of sound waves :

1. 1 : 4

2. 4 : 1

3. 16 : 1

4. 1 : 16

At which temperature the speed of sound in hydrogen will be the same as that of the speed of sound in oxygen at 100°C :

1. – 148°C

2. – 212.5°C

3. – 317.5°C

4. – 249.7°C

The phase difference between two points separated by 1m in a wave of frequency 120 Hz is 90°. The wave velocity is :

1. 180 m/s

2. 240 m/s

3. 480 m/s

4. 720 m/s

The echo of a gunshot is heard 8 sec. after the gun is fired. How far from him is the surface that reflects the sound? (velocity of sound in air = 350 m/s) :

1. 1400 m

2. 2800 m

3. 700 m

4. 350 m

A man sets his watch by the sound of a siren placed at a distance 1 km away. If the velocity of sound is 330 m/s

1. His watch is set 3 sec. faster

2. His watch is set 3 sec. slower

3. His watch is set correctly

4. None of the above

The velocity of sound in air is: