Which pressure does not correspond to 1.25 atm? ( 1 in. = 2.54 cm)?

a. 950 torr b. 950 cm Hg
c. 37.4 in. Hg d. all of the above.
e. none of the above


This is from a test I took. I am trying to learn WHY I got things WRONG

Which pressure does not correspond to 1.25 atm? ( 1 in. = 2.54 cm)?

a. 950 torr b. 950 cm Hg
c. 37.4 in. Hg d. all of the above.
e. none of the above



\frac {1.25\, atm}{1} \, \times\, 760\, \frac {mm\,Hg}{atm} = 950\,mm\,Hg

Note first how I handled the units. I specifically wrote 1.25 atm as a fraction so you can see how "atm" cancels and you're left with "mm Hg"

Note that 1 torr = 1 mm Hg so this is also equal to 950 Torr.

So, "a" is out. "b" is the same as "a", so that's out, too. Let's now convert it to inches of Hg. There are 25.4 mm per inch (that's a good number to remember). Therefore,

\frac {950\, mm\, Hg}{1} \, \times\, \frac {in\,Hg}{25.4\, mm\,Hg} = 37.4\,in\,Hg

That means "c" is out. "a", "b", and "c" are all the same as 1.25 atm so I guess the answer must be "d" - "none of the above does not correspond to 1.25 atm."

If this is the answer you gave your teacher, you send him/her to me and I'll fight it out with him/her. :mad: If it's not, well, I guess you got it wrong. :(