The number of waves contained in unit length of the medium is called

$A$ wave equation is given by $y = 10^{-4} \sin(60t + 2x)$,where $x$ and $y$ are in $meters$ and $t$ is in $seconds$. Which of the following statements is correct?

$A$ wave is represented by the equation: $y = a \sin(0.01x - 2t)$,where $a$ and $x$ are in $cm$. The velocity of propagation of the wave is .... $cm/s$.

The figure shows the wave $y = A \sin(\omega t - kx)$. What is the magnitude of the slope of the curve at $B$?

In a simple harmonic wave,the minimum distance between particles in the same phase always having the same speed is ..........

You have learnt that a travelling wave in one dimension is represented by a function $y=f(x, t)$ where $x$ and $t$ must appear in the combination $x-vt$ or $x+vt$,i.e.,$y=f(x \pm vt)$. Is the converse true? Examine if the following functions for $y$ can possibly represent a travelling wave:
$(a)$ $(x-vt)^2$
$(b)$ $\log[(x+vt)/x_0]$
$(c)$ $1/(x+vt)$