Lesson 5: ACT Science Mastery

Lesson 5: ACT Science Mastery

Passage

• Scientists have found that carbon monoxide gas (CO) is toxic when found in the air above concentrations of 0.1 % by volume. In city areas, automobiles are a significant source of CO. Studies have shown that CO levels in cities are higher during colder weather. A group of students hypothesized that cars emit more CO at colder air temperatures than warmer air temperatures during the first 18 minutes that they are started. The students then performed two experiments to test their hypothesis. 

Experiment 1

A hose was connected to the tailpipe of a car. After the engine was started, the exhaust was collected in a leak-proof bag. From there, a 10 mL 

sample was taken from the bag with a syringe injected into a gas chromatography, which separates mixed gases into their individual components. The students then were able to determine the percentage by volume of CO in the exhaust Samples were taken at 3-minute intervals, with the last sample taken 18 minutes after the end was started. This experiment was conducted four different vehicles with an external air temperature of 22 °C. The results of this expert are shown in Table 1.

Experiment 2

The same study was conducted on the four cars at an external temperature of -7°C results of this experiment are shown in Table 2

Multiple Choice

What percent of CO was present in the exhaust of the 1980 Model A at -7 °C after 6 minutes?

• 4.1%

• 4.4%

• 3.3%

• 7.2%

The correct answer is A.

In Table 1, we look at the column labeled 1980 Model A and find the 6 minutes row. The percent of CO in exhaust on that row is 4.1. 

Multiple Choice

What percent of CO was present in the exhaust of the 1980 Model B at -7 °C after 9 minutes?

• 3.3%

• 7.3%

• 6.9%

• 11.1%

The correct answer is D.

In Table 1, we look at the column labeled 1980 Model B and find the 9 minutes row. The percent of CO in exhaust on that row is 11.1.

Multiple Choice

What percent of CO was present in the exhaust of the 2008 Model B at 22 °C after 3 minutes?

• 2.0%

• 1.0%

• 6.3%

• 0.4%

The correct answer is B.

In Table 2, we look at the column labeled 2008 Model B and find the 3 minutes row. The percent of CO in exhaust on that row is 1.

Multiple Choice

What percent of CO was present in the exhaust of the 2008 Model A at 22 °C after 15 minutes?

• 0.1%

• 0.3%

• 4.9%

• 1.0%

The correct answer is A.

In Table 2, we look at the column labeled 2005 Model A and find the 15 minutes row. The percent of CO in exhaust on that row is 0.1. 

Multiple Choice

What vehicle had the lowest level of CO sent in the exhaust after 18 minutes at -7°C

• 1980 Model A

• 1980 Model B

• 2008 Model A

• 2008 Model B

The correct answer is C.

In Table 1, we look at the row labeled 18 minutes. The lowest number in that row is 0.4, which is in the 2008 Model A column.

Multiple Choice

What vehicle had the highest level of CO sent in the exhaust after 12 minutes at 22 °C?

• 1980 Model A

• 1980 Model B

• 2008 Model A

• 2008 Model B

The correct answer is B.

In Table 2, we look at the row labeled 12 minute The highest number in that row is 6.1, which is the 1980 Model B column. 

Multiple Choice

What was the difference between the percentage of CO in the exhaust of the 1980 Model B after six minutes at the temperature of -7 °C compared to the percentage of CO in its exhaust at the temperature of 22 °C after the same amount of time elapsed?

• 0.9%

• 1.2%

• 0.7%

• 0.8%

The correct answer is A.

The CO level of the 1980 Model B on the 6 minutes row in Table 1 is 7.2. The CO level of the 1980 Model B on the 6 minutes row in Table 2 is 6.3. Subtract to find the difference. 72-6.3 = 0.9. 

Multiple Choice

What vehicle had a time period with a higher level of CO in the exhaust at 22°C than at -7 °C?

• 1980 Model A

• 1980 Model B

• 2008 Model A

• 2008 Model B

The correct answer is D.

To answer this question, you have to find a point on Table 1 which is higher than the same point on Table 2. The only point like this is the 6 minutes row in the 2008 Model B column.