TBR Gen Chem, Chapter 7, Passage 2, Question 14

[sillyjoe]

The question reads:

Which of the following conclusions is INVALID for Compound A?

A. Compound A does not sublime at 25°C.
B. Compound A is solid at 250 K, 760 torr.
C. Compound A has a triple point roughly equal to that of water.
D. For Compound A there exists a solid that is less dense than its liquid phase.

Choice D is correct. Compound A does sublime at 25°C (298 K), if at a pressure below 760 torr; Compound A is a solid at 250 K and 760 torr; and Compound A does have a triple point roughly equal to water (the triple point of water is at 0°C). The only uncertainty is the relative densities of the solid and liquid phases. There is no point at which an increase in pressure at constant temperature converts the solid to a liquid. An increase in the pressure increases the density of the material. This makes choice D the best choice.

Why isn't A an invalid statement?

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[PlumbLine]

Kelvin as opposed to Celsius?


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[sillyjoe]

But doesn't it sublime at 298 kelvin at low pressure?

 

[IslandStyle808]

But doesn't it sublime at 298 kelvin at low pressure?

Sorry I thought I understood this problem but I think I also misunderstood something here. When I did this problem, I thought answer stem was stating that if the pressure were increased or decreased at 25C it won't sublime. Now, I am not sure if this is what the answer choice was saying.

 

[sillyjoe]

Sorry I thought I understood this problem but I think I also misunderstood something here. When I did this problem, I thought answer stem was stating that if the pressure were increased or decreased at 25C it won't sublime. Now, I am not sure if this is what the answer choice was saying.

Do you think it is an error?

 

[IslandStyle808]

Do you think it is an error?

Its possible, maybe in the answer section of the book or it could be that the details were not given in the passage. Tough to say.