What will the reading be if I pass ultrasonic wave towards a metal wall, where I put a CRO beside the transmitter?

A linear equation with a negative slope or y=k with several crests?

define ultrasonic wave... would light technically be ultrasonic wave, because it's a wave and it travels faster then sound.

an ultrasonic wave is a sound wave that is too high frequency for us to hear. hence ultrasonic scan. its kinda like hi-res sonar.

To pass and detect ultrasound trough a metal wall, the simplest way is to cement piezoelectric transducers as emitter side and at the other side as ultrasonic microphone.

Attaching an oscilloscope to the last will show the waveform easily.

 

What would be the waveform? Depends on the fed waveform, bouncing paths, elasticity of material, lenght of propagation, route, attenuation versus frequency response properties...

 

You can obtain a piezoelectric microphone by removing the ringer of a modern defunct telephone. That will work.

 

Miguel