Why V versus P might appear to be straight, based on the range of your data. Use an illustration in addition to your description to clarify your explanation.
For my graph, I have a straight line with a negative slope. I think because the range is small (100 cm H20) that any change to the total volume is slight. I believe that the reason is because in this lab we used a water manometer instead of that of mercury. A column of water supports "13.55" times atmospheric pressure as the mercury column. I remember the instructor saying something the lecture two days ago about elevator being two story high. I don't know how it relates to the lab.
Any clarification and help is appreciated. Thanks!
The graph of volume v. pressure should be a hyperbola since the volume and pressure of a gas vary inversely. However a small variation in pressure (i. e. 100cm H2O / 13.55 H2O/cmHg=7.4 cm of mercury which you have) would produce a near straight line with a negative slope.
You have not told us HOW you varied the pressure in your lab experiment. If you were using a WATER manometer, it would have to be 0.74m x 13.55 = 10 meters high (33 ft.) to vary the pressure by 1 atmosphere. Then your graph would be more curved and look like a hyperbola.