Read the following passage and answer the question that follow :
The data below shows the concentration of nicotine smoked by a smoker taking 10 puffs/minute.
[Graph: "Smoking Cigarette", concentration of nicotine in blood (mg/cm3) against time (minutes), 1 to 15. The line rises steadily from about 0 at 1 minute to a peak of 45 at 10 minutes, falls sharply to 20 at 11 minutes, then declines slowly to about 10 at 15 minutes.]
(a) (i) With reference to the above graph, explain the concentration of nicotine in the blood at 10 minutes.
Show Hint
At 10 minutes continuous puffing has built nicotine up to its peak of 45 mg/cm3.
Step 1: Read the graph:
The graph plots nicotine in blood (mg/cm\(^3\)) against time while the person smokes 10 puffs every minute.
The line climbs in a straight slope from nearly 0 at 1 minute to its highest point at 10 minutes.
At 10 minutes the value is 45 mg/cm\(^3\), the maximum on the whole graph.
Step 2: Explain why it is highest:
Each puff sends nicotine through the lungs into the blood within seconds.
The smoker keeps puffing at a steady rate, so nicotine enters faster than the body can break it down and remove it.
So the level keeps building up for the first 10 minutes and reaches its peak at 10 minutes.
Step 3: What happens after the peak:
Once smoking stops at 10 minutes, no new nicotine arrives.
The level then drops sharply to 20 at 11 minutes and falls slowly afterwards, which confirms that smoking was the cause of the rise.
Final Answer:
At 10 minutes the nicotine concentration is at its maximum (45 mg/cm\(^3\)) because continuous smoking keeps adding nicotine to the blood faster than it is cleared.
