If someone could me with these questions i'd gladly appreciate it

All i know is #8 is C.
sorry I'm not much of help

8).  If two waves meet and combine and the result is twice the size
of either one, then they're both the same size, and they're IN PHASE
with each other at the place where they meet.

9).  A wave loses energy as it moves through a medium.  Not only that,
but even the energy it doesn't lose gets spread out over a greater area
as the sound spreads out.  So the farther you are from the source, the
less able you are to hear the sound.

10).  Statement ' B ' is correct.  Each of the others has something that's
wrong and funny in it.  

  cxrcvbnmbhjtyrtdhfxbv nbmkhturytdsfxc gfxcbmgv vv fgcbvc