One way you could measure this is hitting the two metals with a mallet and seeing which one has more of a dent
The less dense areas in a sound wave is called a rarefaction or rarefactions if there are multiple.
Substance A will sink because it is more dense than water. An object that is more dense than water will sink and an object that is less dense than water will float.
An electron this is the smallest particle and it takes up the least mass because its negative charge makes it harder for electrons to have a place in an atom.
