Question

Many states require annual testing of cars to determine the levels of their CO emissions. Based on the experiments, in order to determine the maximum percent of CO found in a car's exhaust, during which of the following times after starting a car would it be best to sample the exhaust? F. \(1-3\) min G. \(5-7\) min H. \(9-11\) min J. 13 min or longer

Short answer

Answer: 1-3 minutes after starting the car.

Step-by-step solution

Review each time range

Consider each range of time provided in the options, and try to determine which one would most likely result in the highest CO emissions based on general knowledge of how cars operate and their emissions.

Option F: 1-3 min

During the first few minutes after starting a car, the engine and exhaust system are still warming up. During this time, the catalytic converter, which is responsible for reducing CO emissions, may not be working at its optimal efficiency. Therefore, it is likely that CO emissions will be higher during this period.

Option G: 5-7 min

After the car has been running for about 5 to 7 minutes, the engine and exhaust system should be warmed up, and the catalytic converter should be operating at a higher efficiency level. During this time, CO emissions may have decreased from their maximum level during the initial warm-up period.

Option H: 9-11 min

At the 9-11 minute range, the car should be fully warmed up and the catalytic converter should be working effectively. As a result, CO emissions should be lower compared to when the car was just starting or in its initial warm-up phase.

Option J: 13 min or longer

During extended periods of operation, such as after 13 minutes or more, the car's engine and exhaust system should be functioning optimally and CO emissions should be minimized. Hence, this time range would not be ideal for capturing maximum CO emissions.

Choose the best time range

Based on the analysis of each time range, the best time to sample the car's exhaust for maximum CO emissions would be during the initial warm-up phase when the engine and exhaust system components are not yet working at their best efficiency. Therefore, the answer is option F, 1-3 minutes after starting the car.

Key concepts

Scientific Experimentation

When conducting scientific experimentation, it's crucial to follow systematic steps to achieve valid results. In our example regarding CO emissions from cars, the experiment focuses on determining the optimal time to measure the highest concentration of CO. Initial hypotheses can be drawn from understanding the warm-up phases of a car's engine and the role of a catalytic converter. Experimentation in science isn't just about conducting the tests; it's about setting clear parameters—like specific time intervals in this case—to collect data systematically.

For students preparing for the ACT Science section, this translates to understanding the experimental set-up and predicting outcomes based on scientific principles. Grasping the concept of experimental timing can be key in real-world contexts, not just in standardized tests. Students should also recognize that accurate measurements are paramount and proper timing can make a significant difference in the validity of experimental outcomes.

Data Analysis

Data analysis is the backbone of scientific inquiry. It involves reviewing information and using logical reasoning to draw conclusions. In the context of our textbook problem on CO emissions testing, analyzing the data means carefully examining each time interval and understanding the car's emission behavior at these distinct phases. Effective data analysis requires knowledge of the system being studied—in this case, the warm-up cycle of a car's engine and emission control system.

A student must glean insights from what is known about car emissions and apply this to the information given. For instance, knowing that a catalytic converter takes time to reach optimal efficiency allows a student to rule out later times when the car has been running and the emissions are likely to have decreased. This approach to data analysis is valuable preparation for the ACT Science section, where the ability to interpret data from tables, graphs, and experiments is frequently tested.

Environmental Science

Understanding environmental science is fundamental for comprehending experiments related to CO emissions. It deals with the principles concerned with the environment and the effects of human activity on natural processes. The role of cars in emitting CO, a harmful pollutant, is a classic study case within environmental science.

Through the lens of environmental science, the question from our textbook—targeting the measurement of CO levels at different times after starting a car—teaches students about the environmental impact of pollutants and the importance of emission controls like the catalytic converter. This real-world application helps students appreciate the breadth of environmental science, which is more than just a subject—it's an interdisciplinary field that touches on technology, chemistry, policy, and public health. For those preparing for the ACT, understanding environmental science concepts can support questions related to experimental design, data analysis, and other topics that require thinking beyond the classroom.