If I remember correctly (from my studies long time ago) the layers are from the outer to the center:
SiAl : Silicon-Aluminum
SiMa : Silicon-Magnesium (although should be Mg)
NiFe : Nickel-Iron
The SiMa layer should have the lightest elements (Magnesium is lighter than Aluminum)
You are correct!
Happy to assist you!
Answer:
The height is 3.1m
Explanation:
Here we have a conservation of energy problem, we have a conversion form eslastic potencial energy to gravitational potencial energy, so:

then we have only gravitational potencial energy when the ball is at its maximun height.

because all the energy was transformed Eg=Ee

searching the web, the mass of a ping pong ball is 2.7 gr in average. so:

Since you are looking for the speed, you need to rearrange the formula which is f = speed / wavelength. That should give you speed = f (wavelength.) All you need to do next is to substitute the value to the following equation. speed = 250 Hz (6.0m) that should leave you with 1500 m/s which is very fast.