When a wave travelling in a medium is reflected from the boundary of a denser medium,which of the following will not change?

The wave function of a pulse is given by $y = \frac{5}{(4x + 6t)^2}$,where $x$ and $y$ are in $m$ and $t$ is in $s$. The velocity of the pulse is ......... $m/s$.

If the wavelength of a wave is $\lambda = 6000 \mathring{A}$,then the wave number will be:

Two points are located at a distance of $10\; m$ and $15 \;m$ from the source of oscillation. The period of oscillation is $0.05 \;s$ and the velocity of the wave is $300 \;m/s$. What is the phase difference between the oscillations of the two points?

$A$ transverse wave of amplitude $0.5\, m$,wavelength $1\, m$,and frequency $2\, Hz$ is propagating in a string in the negative $x$-direction. The expression for this wave is:

$A$ plane progressive wave is represented by the equation $y = 0.1 \sin \left( 200\pi t - \frac{20\pi x}{17} \right)$,where $y$ is displacement in $m$,$t$ is in seconds,and $x$ is the distance from a fixed origin in meters. The frequency,wavelength,and speed of the wave respectively are: