Here is what i think are the right answers
5.(D)...filter suspended soilids, then evaporate.
7.(C) basic metal oxides react with acids to make salts etc..only U or V would be amphoteric
8.(A) as mentioned before, double concent, then -log(H+)
9.(A) i put C in the test and forgot the whole alphabetical stuff
10.(A)... it says based on these data ALONE
12.(D) it seems its right, but can someone tell me how you actually do it!?
13.(D) 1. X>Y 2. Z>Y 3. X<Z therefore, Z>X>Y
14. (dont know, pretty hard)
15. (dont know, i was told its C because after initial shock, buffer maintains constant pH)