Which one of the following quantities is generally not obtainable from a single heating or cooling curve of a substance, measured at atmospheric pressure?
a. melting point
b. boiling point
c. triple point
d. heat of fusion
e. heat of vaporization

C. triple point  

Explanation:

It is rare for a substance to have a triple point at 1 atm, so you can't measure it if you are limited to 1 atm.

It's easy to measure the melting point and boiling point, because they are the horizontal portions of the curve.

If you are adding heat at a constant rate, you can determine the heats of fusion and vaporization by measuring the times it takes for the substance to completely melt or vaporize.

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