Step-by-step explanation:
on the x axis your labels should object identity and you can put a different object every 2cm or 3cm depending on which can fit all the 5 objects on it. on the y axis, label as length then have a scale of either 2cm or 4cm for one unit length.
for plotting the graph, use "x" for the points in inches then use "o" for the points in cm. include a key/legend of this on your graph paper. draw a line connecting all the x plots and another separate line connecting o plots.
marks are usually awarded for label of axis, title of graph(relationship between an objects length in inches and centimeters). your scale for the axis and the key/legend
only use pencil and capitalize your titles
for the last question, the relationship between the object in inches and cm, observe your graph, does the length in inches increase as the length in cm increases? are they proportional? meaning that if one increases so does the other and vice versa