[osky1]

Can anyone help please ? The major peaks in the mass spectra of two hydrocarbons A and B are shown below.
Compounds A and B have the same empirical formula. a)   Deduce the molecular formula of each compound.
Compound A
Compound B
(c)  Suggest the species responsible for the peak at m/e 41 in the spectrum compound B.

[Arkcon]

Cute spectra ... they really want to be sure you're paying attention, using different ordinate axes for two graphs you're supposed to compare.  What do you know, or just learned about, or were supposed to read about mass spectroscopy that will begin to solve this problem for yourself?  Can you find the parent ion?  How was the sample ionized -- why would they make a point about the 41 ion?

[osky1]

hey thanks do you know how to Deduce the molecular formula of each compound? hope you can help thank you

[Arkcon]

I'm not an expert in fragmentation, most of the mass spec I do, the instrument does all the work.  However, you've been told a lot of useful information, you just have to use it:  this is a hydrocarbon, only H and C.  The mass spec will tell you the ... well ... molecular mass.  What is it?  And once you know it, what two molecules, with the same empirical formula, but different molecular formulas, will give you the different fragments you see?

[osky1]

Suggest the species responsible for the peak at m/e 41 in the spectrum compound B. how do i go about it?

[Borek]

Think what possible combinations of C (12) and H (1) will give 41.