Mass Spectrum

I am stuck on this question. How do you know what the numbers are on the y axis and how do you go about working it out. This is from pmt and i have attached the link below. The question I'm referring to is 1b. Thanks

https://www.physicsandmathstutor.com/pdf-pages/?pdf=https%3A%2F%2Fpmt.physicsandmathstutor.com%2Fdownload%2FChemistry%2FA-level%2FTopic-Qs%2FAQA%2FPhysical-I%2F1.1-Atomic-Structure%2FSet-F%2FMass%2520Number%2520and%2520Isotopes%25201%2520QP.pdf

You don’t need to know them - you can just count the number of divisions (e.g at m/z = 124, the peak is 2 divisions high).

Thanks! I don't know how that didn't occur to me. Lol

And as for the second part of your question, do you know how to calculate relative atomic mass when you have intensities rather than percentage abundances?

by intensities do you mean abundance? If you mean intensities then i don't know. I know percentage abundance and abundance calculations, cos i think you just input the values into the equation RAM= (mass x abundance) + (mass x abundance) then divide by the total abundance rather than 100%. Also I am stuck on another question I dont know how you find molecular mass in mass spectroscopy. Stuck on question 5 and 6.1
https://filestore.aqa.org.uk/resources/chemistry/AQA-7404-7405-SG-TOFMS-QA.PDF

X

Intensity in this context refers to the height of
the peak, which in turn is proportional to the percentage abundance of the isotope.

With Q’s 5 and 6.1, you need to be aware that the m/z ratio = the relative molecular mass of the ion(s) responsible for the peaks (since at A level, you assume the ions have a charge of +1).

For Q5, what are the mass numbers of the two isotopes of chlorine? How might this help in light of the above?

For Q6.1, when you ionise larger molecules, they often fragment into smaller ions. Which peak is most likely caused by the unfragmented molecule? How might that help?

Ok so for Q5, I would divde 70, 72, 74 all by 2, as you need to divide the mass by the charge which is 2 to get 35, 36, 37
And for 6.1 so do you look at the highest m/z value, which is the unfragmented one, which is 56, so it wont be 57 as thats probably fragmentated.
Thank you for this, I had to read the questions over over again until i understood