Answer:
a) Gradient = rise/run = mass/volume
since the graph is mass against volume we know mass is on the y-axis and volume is on the x-axis
in physics it’s best to use a larger part of the graph to find the gradient, so imma use the biggest values.
90/4.5 = 20
(additional note: sometimes you may get a different gradient. For example, when using 30 and 1.4 you get ≈21 this is an anomalous result since ita gradient differs; a mass against volume graph is supposed to be linear)
b) gradient represents density (p) since gradient is = mass/volume. And density also = mass/volume
For c and d just plot the points and you’ll be able to read from the graph to get the values.
I got this graph (the image)
but you’ll be able to interpret better when ‘you’ draw it (so try plotting it)