Why cannot mechanical wave travel in vacuum?​

Because mechanical waves rely on particle interaction in order to transport their energy, they cannot travel through regions of space that are void of particles. That is, mechanical waves cannot travel through a vacuum.

Explanation:

Since mechanical waves depend on molecule cooperation to move their energy, they can't go through areas of room that are drained of particles. That is, mechanical waves can't go through a vacuum.

Explanation:

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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