Liquids

Question

A chemist knows the following about the colorless liquid in a certain beaker. 

(1) If chemical X is added to the liquid, it will turn red
(2) If chemical Y is added to the liquid it will turn blue
(3) If both X & Y are added to the liquid it will turn green

Given the statements above, which of the following must be true?

1) If the liquid remains colorless, then no chemicals were added
2) If the liquid turns green, then both X & Y were added 
3) If the liquid turns blue, then chemical X was not added
4) If the liquid turns blue, then it is possible that chemical Y was added
5) If the liquid remains colorless, then it is possible that chemical X and only chemical X was added

kpadma · Answer

I would go with A.

Paul · Answer

D is most conservative choice

Paul · Answer

What if chemical Z was added and makes it colorless?

anandnk · Answer

This is really a tough question.

From logic point of view A stands out.

if A then C if not C then not A
if B then D if not D then not B

So not( C or D ) = colorless = not A and not B


Choice (D) 4 as Paul mentioned is the most diplomatic answer.

hallelujah1234 · Answer

B <> --> A and A --> B are consistent, hence 4 is correct. <> = possibility

Paul · Answer

A) What if Z makes the liquid transparent? Then we cannot say that if liquid is transparent, nothing was added
B) What if W also makes the liquid turn green? Then we cannot confirm for sure that X&Y were added
C) What if X+Z also makes liquid turn blue? We then cannot tell that X was not added for sure
D) If liquid turns blue, then yes,  it is possible  that Y was added (because something else could also have been added to make liquid turn blue). D is therefore consistent.
E) 1 says that if X is added, it will turn red...

anandnk · Answer

I believe D is the answer.

The choice is clearly between A and D. But A has a fundamental flaw. A says no chemicalswere added. A would have been correct had it said  neither X nor Y was added. 

 
I spilled orange juice on my laptop and someofmy keys are stuck.So dont get mad if you dont see a space between someof the words in my sentence.

lvb9th · Answer

As I was posting the question, I was going to make a statement that Paul is going to take this question apart and put it back together, not just simply answer it with an explanation to the answer he choses. I think we all have much to learn from him when it comes destroying all the wrong answers, in turn coming up with the only one correct: Well done, D it is :panel

Liquids

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