Which one of the following does not represent a travelling wave?

$A$ transverse wave travelling along a stretched string has a speed of $30 \ m/s$ and a frequency of $250 \ Hz$. The phase difference between two points on the string $10 \ cm$ apart at the same instant is

The transverse displacement $y(x, t)$ of a wave on a string is given by $y(x, t) = e^{-(ax^2 + bt^2 + 2\sqrt{ab}xt)}$. This represents a

The distance between two consecutive points with phase difference of $45^{\circ}$ in a wave of frequency $300 \text{ Hz}$ is $4.0 \text{ m}$. The velocity of the travelling wave is (in $\text{km/s}$):

$A$ travelling acoustic wave of frequency $500 Hz$ is moving along the positive $x$-direction with a velocity of $300 ms^{-1}$. The phase difference between two points $x_{1}$ and $x_{2}$ is $60^{\circ}$. The minimum separation between the two points is:

$A$ transverse wave is given by $y = A \sin 2\pi \left( \frac{t}{T} - \frac{x}{\lambda} \right)$. The maximum particle velocity is equal to $4$ times the wave velocity when: