Which of the following equation represents a wave ?

A wave enters to water from air.  In air frequency, wavelength, intensity and velocity are

In water the corresponding quantities are 

The transverse wave represented by the equation

A standing wave having 3 nodes and 2 antinode is formed between two atoms having a distance 1.21   between them,  The wavelength of the standing wave is

A vehicle, with a horn of frequency n is moving with a velocity of 30 m/s in a direction perpendicular to the straight line joining the observer and the vehicle.  The observer perceives the sound to have a fequency n + n₁.  Then (If the sound velocity in air is 300 m/s)

Velocity of sound waves in air is 330 m/s.  For a particular sound wave in air, path difference of 40 cm is equivalent to phase difference of 

The phase difference between two waves represented by

where x is expressed in metre and t is expressed in second, is approximately

Standing wavesare produced in a 10 m long stretched string.  If the string vibrates in 5 segments and the wave velocity is 20 m/s, the 5 segments and the wave velocity is 20 m/s, the frequency is

A standing wave is represented by y =a sin (100t ) cos (0.01)x, where y and a are in millimetre, t in seond and x is in metre.  Velocity of wave is

The speed of a wave on a medium is 760 m/s.  If 3600 waves are passing through a point in the medium in 2 minutes, then their wavelengths are