AAMC 8 Physical Sciences, Question 5

[Natasha1989]

I don't know why C is the correct answer:

5. Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?
A) It is a gas at room temperature
B) A 1 M solution freezes below 0 degrees celsius
C) A 1 M solution conducts electricity
D) It is composed of two nonmetals

I chose answer A, but it's not right.

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[SoftwareKevin]

A: Ionic compounds are solids at room temperature, so that would not be a reason to say it's ionic
B: Freezing point depression is not characteristic of just ionic compounds (think antifreeze), so it would not be a reason to say it's ionic
C: Ionic solutions are electrolytes, so if you put something in water and saw it conducted current, you might want to say it's ionic
D: Ionic compounds are usually a metal + nonmetal, so it wouldn't make sense to say it's ionic because of two nonmetals.

C is the best answer.

I don't know why C is the correct answer:

5. Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?
A) It is a gas at room temperature
B) A 1 M solution freezes below 0 degrees celsius
C) A 1 M solution conducts electricity
D) It is composed of two nonmetals

I chose answer A, but it's not right.

 

[zer0crew]

This question got me pretty good too, even after reading the answer I still had some trouble understanding it. Some weird double-negatives going on...

Eventually I found the best way of looking at it was this;

"Which single property of HCl makes it APPEAR ionic, even though you know for a fact that it isn't?"

 

[PharMed2016]

I don't know why C is the correct answer:

5. Which of the following statements is consistent with the incorrect conclusion that HCl is an ionic compound?
A) It is a gas at room temperature
B) A 1 M solution freezes below 0 degrees celsius
C) A 1 M solution conducts electricity
D) It is composed of two nonmetals

I chose answer A, but it's not right.

Just think about it a little and systematically go through all the answer choices available.

A. It is a gas at room temperature. Incorrect - there are many non-ionic compounds that are gases at room temperature such as CO2.
B. A 1 M solution freezes below 0 degrees celsius. Incorrect - freezing point is not an ionic property. I notice you are a pharmacy student so think back to pharmaceutics. Think back to pharmaceutics I-II, freezing point depression is a colligative property.
C. A 1 M solution conducts electricity. Correct - usually we associate the ability to conduct electricity with metals or ionic compounds. HCl therefore having this ability may mislead us into thinking that it is in fact ionic when it really isn't. Just one of those exceptions to the rules.
D. Composed of two nonmetals. Incorrect - this is a gimme. This is what definition of a non-ionic compound is.

Hopes this helps.

 

[KababMD]

this question had my head spinning for some time as well. I didnt know if this was an error, or what I thought they wanted another INCORRECT statement...I picked D, even though I reasoned C being correct

 

[jackhughes]

This question got me pretty good too, even after reading the answer I still had some trouble understanding it. Some weird double-negatives going on...

Eventually I found the best way of looking at it was this;

"Which single property of HCl makes it APPEAR ionic, even though you know for a fact that it isn't?"

Thank you google for finding this thread, and thank you zer0crew for that explanation/re-wording.

Not going to lie, the original 'phrasing by AAMC' would have angered any English teacher. Honestly, who speaks like that?!

 

[rsrchchmcl21]

haha i'm going through this 8 years later. thank you guys for clarification.