Which of the following is the example of transverse wave

A block $\mathrm{M}$ hangs vertically at the bottom end of a uniform rope of constant mass per unit length. The top end of the rope is attached to a fixed rigid support at $O$. A transverse wave pulse (Pulse $1$ ) of wavelength $\lambda_0$ is produced at point $O$ on the rope. The pulse takes time $T_{O A}$ to reach point $A$. If the wave pulse of wavelength $\lambda_0$ is produced at point $A$ (Pulse $2$) without disturbing the position of $M$ it takes time $T_{A 0}$ to reach point $O$. Which of the following options is/are correct?

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[$A$] The time $\mathrm{T}_{A 0}=\mathrm{T}_{\mathrm{OA}}$

[$B$] The velocities of the two pulses (Pulse $1$ and Pulse $2$) are the same at the midpoint of rope.

[$C$] The wavelength of Pulse $1$ becomes longer when it reaches point $A$.

[$D$] The velocity of any pulse along the rope is independent of its frequency and wavelength.

To increase the frequency from $100 Hz$ to $400 Hz$ the tension in the string has to be changed by ..... $times$

A pipe closed at one end produces a fundamental note of $412\,Hz.$  It is cut into two pieces of equal length the fundamental notes produced by the two pieces are

In a sonometer wire, the tension is maintained by suspending a $50.7 kg$ mass from the free end of the wire. The suspended mass has a volume of $ 0.0075 \, m^3$. The fundamental frequency of the wire is $260 Hz$. If the suspended mass is completely submerged in water, the fundamental frequency will become .... $Hz$ (take $g = 10 ms^{-2}$)

Standing waves are produced in a $10 \;m$ long stretched string. If the string vibrates in $5$ segments and the wave velocity is $20\; m/s$, the frequency is ... $Hz$