What is the Solution to AP Chemistry 2006 Form A Free Response Question #5?

[future_chemist]

Homework Statement

I'm doing #5 in this Ap Chemistry 2006 Form A Free Response Questions. Here's the link http://www.collegeboard.com/prod_downloads/student/testing/ap/chemistry/_ap06_frq_chemistry.pdf

Homework Equations

N/A

The Attempt at a Solution

I think i got the first 3 parts right. Here's what i came up with.

a. X = Na2CO3
Y = KCl
Z = MgSO4

b. OH- + Mg+2 -> Mg(OH)2

c. X has a PH greater than 7 because the its solution contains OH-

 

[chemisttree]

Answers look good except for 'c'. The answer is not false but is not the answer to the question asked. The presence of OH- must be backed up by more information, especially a reaction indicating where the OH- came from.

 

[future_chemist]

I got it figured out already. Thanks anyway. Please close this thread if you don't mind :)