Ideal as a self-study text to build students' knowledge and It was written to cover the calculations in UK AS and A level chemistry syllabuses (roughly for agesyears), but chemistry calculations are just the same A mass to charge ratio (m/z) ofshows that a +1 ion has a mass of The relative heights of the peaks show the relative abundance. Draw a straight line at the point you wish to draw a tangent parallel to the line. Calculate the gradient by m= change in y change in x. As lower level mathe