Urgent. I need explanation please.

Hi, don't fret. The question is just on osmosis. The graph, draw a y axis corresponding to your result range (aka the +0.40 etc.) then at y=0 draw a horizontal line to be your x axis. The values on the x axis is your sugar content. Then plot the graph accordingly, the line should cross 0 between 12 and 14. This is your graph.

For part b, you are right. A has the most sugar in the same volume. Or g/cm3, which is concentration. For part c, when they ask for sugar concentration in the cell, they mean to ask when there's no water going in or out. This is because when the sugar content outside is the same as inside the cell, there's no concentration gradient. So, you need to find at which sugar concentration the mass change is 0. You know that 0 lies between the positive and negative values, so the sugar content should lie between 12-14g per 100cm3. Your graph should also reflect this.

Part c, f increases in mass because the sugar content outside is lower than inside the cells. Which also mean that the water content outside is more than inside. Water will move by osmosis up the sugar concentration gradient into the cell, causing it to increase in mass.

Part d, accuracy is a measure of how close your results are to the "right" point. To increase it, you can repeat the experiment at the same concentrations more times. You can also try to repeat the experiment with more concentrations.