Question

Two astronauts cannot hear each other on moon. why????

Answer 1

Material medium is nessasary for the proportion of sound. on the moon there is vacuum and hence sound cannot propogate on moon thus the astronauts cannot hear each other....

Answer 2

ANSWER

For the propagation of sound some material medium is required.

Sound cannot travel without a medium

On moon there is vacuum and no atmosphere thus astronauts are unable to hear each other out there.