Explanation in DAT Bootcamp

[flossit]

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Hi, will this be most of the time true....?
This is from the explanation after the sample test of Gen Chem.
...Using multiple-choice strategy, the answer cannot be in the middle, so it must be one of the extremes. So the answer is between choice A,...
Please anyone!

This is question 9 from DAT Exam #1, can anyone explain it too please! I thought we are getting 1 ion of Na+ and 3 ions of PO4 in choice D, but the explanation is the other way around.

 

[Artdent97]

Can you post the whole question?

 

[cacajuate]

Na+1 and PO4 3-.

That's Na3PO4. 3 Na+ and 1 PO4 3- ion.

you need to balance out the -3 charge on the phosphate ion with 3 sodiums which each have a +1 charge.

It is saying the answer can't be in the middle because only have 1 vant hoff factor wouldn't give you the largest m to lower the freezing point the most, so it has to be on the extreme answers with the largest vant hoff factor. It has nothing to do with the answer can't be one of the middle multiple choice answers.


I'd work on the basics before I started taking those bootcamp tests.

 

[flossit]

Thank you!