Okay, I may go off and do further research on some of these but here are the ones I know about definitely:
Scratching is what DJs do when they put their fingers on the records and move them backwards and forwards when they're playing so the piece stops, rewinds, starts, stops, rewinds, starts etc and it sounds a bit like a scratching noise (really hard to describe!)
The Sackbut is an ancestor of the modern trombone.
http://en.wikipedia.org/wiki/SackbuttThe Cornett is NOT a cornet - don't get the two confused! Here is some information on the cornett
http://en.wikipedia.org/wiki/CornettThe Shawm -
http://en.wikipedia.org/wiki/ShawmThe Crumhorn -
http://en.wikipedia.org/wiki/Crumhorn(I'm a big fan of wikipedia!)
Flanging -
http://en.wikipedia.org/wiki/FlangingStrumming is what guitarists do when they aren't playing a tune, they're playing all the strings of the instrument in a chord (imagine singing round a campfire with a guitarist doing the accompaniment - they would be strumming).
The difference between sliding and pitch bending: sliding would be sliding from one pitch to another. Pitch bending is where you just taking the pitch of one note and bend it just out of tune (normally take it flat) and back again.
Bass could be lots of different things. Obviously, any instrument that is playing the lowest part of anything in harmony is playing the bass line.
Bass could be a bass singer or it could be referring to the double bass or bass guitar.
Good luck with the listening exam!