You can use the graph to find out the average volume of carbon dioxide gas given off per second in the period between 10 seconds and 30 seconds. To do this you should draw a line at 10 seconds on
the horizontal axis up to where it meets the line of the graph. Then draw another line up at 30
seconds. Draw a line across as shown in the graph below.
70
60
50
40
volume of carbon
dioxide / cm3
30
20
10
0
20
40
60
80
100
time / s​

If a small-diameter open glass tube is partially immersed in a vessel containing mercury, the surface of the mercury inside the tube will be a. lower than the mercury in the vessel, and shaped like the inside of a bowl. b. higher than the mercury in the vessel, and shaped like the inside of a bowl. c. lower than the mercury in the vessel, and shaped like the outside of an umbrella. d. higher than the mercury in the vessel, and shaped like the outside of an umbrella.