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Junkao Science Knowledge study materials
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Junkao Science Knowledge practice questions

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Question 1Scientific Inquiry and Experimental Design

A researcher wants to test whether a new fertilizer increases tomato plant height. Which variable should be manipulated by the researcher in this experiment?

  1. Height of the tomato plants
  2. Amount of water given
  3. Amount of fertilizer applied Correct answer.
  4. Type of soil used

Explanation

The independent variable is the factor the researcher deliberately changes to observe its effect. Here the fertilizer amount is what is being tested, so it is the manipulated variable. Plant height is the outcome measured, making it the dependent variable.

Question 2Scientific Inquiry and Experimental Design

In a controlled experiment, why is a control group included?

  1. To remove the need for repeated trials
  2. To increase the total number of subjects tested
  3. To provide a baseline for comparison without the treatment Correct answer.
  4. To ensure the hypothesis is proven correct

Explanation

A control group is treated identically to the experimental group except that it does not receive the independent variable. It establishes a baseline so any change in the experimental group can be attributed to the treatment. Without it, observed effects could be due to other factors.

Question 3Scientific Inquiry and Experimental Design

A scientist records the temperature of a solution every minute for ten minutes. Which term best describes these recorded temperature values?

  1. Data Correct answer.
  2. Hypothesis
  3. Theory
  4. Conclusion

Explanation

Recorded observations and measurements collected during an investigation are called data. Data may be quantitative, such as temperature readings, or qualitative descriptions. A hypothesis is a testable prediction, while a theory is a broad explanation supported by much evidence.

Question 4Scientific Inquiry and Experimental Design

Which action best improves the reliability of an experimental result?

  1. Changing several variables at once
  2. Using only one subject in the study
  3. Reporting only the results that fit the hypothesis
  4. Repeating the experiment several times Correct answer.

Explanation

Reliability refers to consistency of results when an investigation is repeated. Repeating trials and averaging results reduces the influence of random error. Changing multiple variables or using a single subject introduces confounding and variability.

Question 5Scientific Inquiry and Experimental Design

A student measures the mass of a sample three times and obtains 5.02 g, 5.01 g, and 5.03 g, while the accepted value is 4.50 g. How should these measurements be described?

  1. Precise but not accurate Correct answer.
  2. Accurate but not precise
  3. Neither accurate nor precise
  4. Both accurate and precise

Explanation

Precision reflects how closely repeated measurements agree with each other, while accuracy reflects closeness to the true value. The three readings cluster tightly together, so they are precise. However, all lie far from the accepted 4.50 g value, so they are not accurate.

Question 6Scientific Inquiry and Experimental Design

Which of the following is the best example of a testable scientific hypothesis?

  1. Everyone should prefer warm weather.
  2. Some things happen for no reason at all.
  3. Adding salt to water raises its boiling point. Correct answer.
  4. Water is the most beautiful substance on Earth.

Explanation

A scientific hypothesis must be a testable, falsifiable prediction about an observable relationship. The statement about salt raising boiling point can be tested by measurement and could be shown false. Statements about beauty, preference, or causeless events cannot be tested empirically.

Question 7Scientific Inquiry and Experimental Design

A researcher places a thermometer in a beaker of water and reads 22.0 °C. Which statement describes this reading?

  1. A hypothesis
  2. A quantitative observation Correct answer.
  3. An inference
  4. A qualitative observation

Explanation

Observations that involve measurements or numbers are quantitative. A temperature reading of 22.0 °C is a numerical measurement, so it is quantitative. Qualitative observations describe qualities such as color or texture without numbers.

Question 8Scientific Inquiry and Experimental Design

A scientist wants to determine whether light intensity affects the rate of photosynthesis in pondweed. Which is the most appropriate dependent variable?

  1. Distance of the lamp from the plant
  2. Number of oxygen bubbles produced per minute Correct answer.
  3. Temperature of the water
  4. Duration of the experiment

Explanation

The dependent variable is the response that is measured and is expected to change with the independent variable. Here light intensity is manipulated, so the rate of photosynthesis, indicated by oxygen bubbles per minute, is measured. Distance of the lamp is the manipulated factor, and temperature and duration are controlled.

Question 9Scientific Inquiry and Experimental Design

Why is it important to keep all variables except the independent variable constant in a controlled experiment?

  1. To eliminate the need for a control group
  2. To make the experiment finish more quickly
  3. To guarantee the hypothesis will be supported
  4. To ensure any observed effect can be attributed to the independent variable Correct answer.

Explanation

Controlling extraneous variables prevents them from influencing the dependent variable. This allows the researcher to attribute changes in the outcome to the manipulated variable. Without control, alternative explanations for the results remain possible.

Question 10Scientific Inquiry and Experimental Design

A student claims that a plant grew taller because it was spoken to daily. Which additional evidence would most strengthen this claim?

  1. A description of the plant's leaf color
  2. A comparison group of identical plants not spoken to Correct answer.
  3. An opinion from a friend about the plant
  4. A single measurement taken at the end

Explanation

To support a causal claim, a comparison with a group that differs only in the proposed cause is needed. A control group of identical plants not spoken to allows the effect of talking to be isolated. A single measurement, an opinion, or a qualitative description does not provide such comparison.

Question 11Scientific Inquiry and Experimental Design

Which measurement tool would be most appropriate for determining the volume of a liquid accurately in a laboratory?

  1. Thermometer
  2. Graduated cylinder Correct answer.
  3. Stopwatch
  4. Triple-beam balance

Explanation

A graduated cylinder is marked with volume graduations and is designed to measure liquid volume. A balance measures mass, a stopwatch measures time, and a thermometer measures temperature. Matching the instrument to the quantity is essential for valid data.

Question 12Scientific Inquiry and Experimental Design

A dataset shows that as the temperature of a gas increases at constant pressure, its volume increases. Which statement best describes this relationship?

  1. Temperature decreases as volume increases.
  2. Temperature and volume are unrelated.
  3. Temperature and volume are directly proportional. Correct answer.
  4. Temperature and volume are inversely proportional.

Explanation

When one variable increases as the other increases, the variables are directly proportional. The observation that volume rises with temperature at constant pressure reflects this direct relationship. An inverse relationship would mean one variable falls as the other rises.

Question 13Scientific Inquiry and Experimental Design

What is the primary purpose of peer review in the scientific process?

  1. To repeat the experiment in a different laboratory
  2. To confirm that the researcher's hypothesis was correct
  3. To evaluate the quality and validity of research before publication Correct answer.
  4. To decide which scientist receives the most funding

Explanation

Peer review subjects a study to scrutiny by independent experts who assess its methods, evidence, and conclusions. It helps identify flaws and improves the quality of published research. It does not confirm hypotheses or replicate experiments directly.

Question 14Scientific Inquiry and Experimental Design

A scientist observes that ice melts faster in a warm room than in a cold room and proposes an explanation. Which step of the scientific process does proposing this explanation represent?

  1. Collecting data
  2. Drawing a conclusion
  3. Forming a hypothesis Correct answer.
  4. Communicating results

Explanation

A hypothesis is a proposed, testable explanation for an observation. After observing that ice melts faster in warm conditions, the scientist offers an explanation that can be tested. Collecting data and drawing conclusions come later in the process.

Question 15Scientific Inquiry and Experimental Design

A researcher tests a new drug on 200 volunteers and gives 100 of them an inactive pill. What is the inactive pill called?

  1. A control variable
  2. An independent variable
  3. A dependent variable
  4. A placebo Correct answer.

Explanation

A placebo is an inactive treatment given to a control group so participants cannot tell whether they received the real treatment. This helps separate the true effect of the drug from expectation effects. Control variables, by contrast, are factors held constant.

Question 16Scientific Inquiry and Experimental Design

In an experiment, a student measures the length of a metal rod as 12.4 cm. Which characteristic of the measurement is described by how close this value is to the true length of 12.4 cm?

  1. Accuracy Correct answer.
  2. Validity
  3. Precision
  4. Reliability

Explanation

Accuracy describes how close a measured value is to the accepted or true value. If the measured 12.4 cm matches the true length, the measurement is accurate. Precision instead concerns the closeness of repeated measurements to each other.

Question 17Scientific Inquiry and Experimental Design

A graph plots plant growth against the amount of light received. The line of best fit shows a positive slope. What does the positive slope indicate?

  1. Growth increases as light received increases Correct answer.
  2. Light received decreases as growth increases
  3. Growth decreases as light received increases
  4. Growth is independent of light received

Explanation

A positive slope on a graph means that as the value on the horizontal axis increases, the value on the vertical axis also increases. Here that means greater light received is associated with greater growth. A negative slope would indicate the opposite trend.

Question 18Scientific Inquiry and Experimental Design

Which of the following best describes a scientific theory?

  1. A personal opinion held by a scientist
  2. A guess made before any investigation
  3. A single measurement recorded during an experiment
  4. A well-supported explanation for a broad set of observations Correct answer.

Explanation

In science, a theory is a comprehensive explanation supported by extensive evidence and repeated testing. It is far stronger than a guess or an opinion. A single measurement is data, not a theory.

Question 19Scientific Inquiry and Experimental Design

A researcher wants to reduce bias when assigning participants to treatment and control groups. Which procedure is most appropriate?

  1. Random assignment of participants to groups Correct answer.
  2. Letting the researcher choose group members
  3. Assigning the first 50 arrivals to the treatment group
  4. Assigning volunteers to the group they prefer

Explanation

Random assignment gives each participant an equal chance of being placed in any group, which balances unknown variables across groups. This reduces selection bias and strengthens causal inference. Letting preferences or researcher judgment decide can systematically skew the groups.

Question 20Scientific Inquiry and Experimental Design

A study reports that students who eat breakfast score higher on tests. Which conclusion is most justified by this correlational finding?

  1. Breakfast has no relationship with test scores.
  2. Eating breakfast is associated with higher test scores. Correct answer.
  3. Eating breakfast causes higher test scores.
  4. Test scores cause students to eat breakfast.

Explanation

Correlational data show that two variables are associated, but they cannot by themselves establish causation. Other factors, such as socioeconomic status or study habits, could influence both breakfast habits and scores. A causal claim would require a controlled experiment.

Question 21Scientific Inquiry and Experimental Design

A student wants to test how the concentration of acid affects the rate of reaction with marble chips. Which factor should be varied?

  1. Mass of the marble chips
  2. Temperature of the room
  3. Size of the marble chips
  4. Concentration of the acid Correct answer.

Explanation

The independent variable is the factor deliberately changed to observe its effect. Here the question asks how acid concentration affects reaction rate, so concentration is varied. Mass, temperature, and chip size must be held constant to isolate the effect of concentration.

Question 22Scientific Inquiry and Experimental Design

Why do scientists generally prefer a larger sample size in an experiment?

  1. It reduces the influence of random variation on the results Correct answer.
  2. It eliminates the need for controlled variables
  3. It makes the experiment more difficult to replicate
  4. It guarantees that the hypothesis is correct

Explanation

A larger sample reduces the impact of random variation and makes results more representative of the population. This improves the statistical reliability of conclusions. However, sample size does not guarantee a correct hypothesis or remove the need for controls.

Question 23Scientific Inquiry and Experimental Design

A scientist uses a ruler marked in millimeters to measure the length of a leaf. What is the smallest change in length that can be reliably detected with this ruler?

  1. 1 micrometer
  2. 1 centimeter
  3. 1 millimeter Correct answer.
  4. 1 meter

Explanation

The resolution of a measuring instrument is the smallest increment it can distinguish. A ruler marked in millimeters has a resolution of 1 mm, so it cannot reliably detect smaller changes. Choosing an instrument with appropriate resolution is important for valid data.

Question 24Scientific Inquiry and Experimental Design

A researcher reports that a new teaching method improved scores by an average of 5 points, but the result was not statistically significant. What is the most appropriate interpretation?

  1. The study should be discarded entirely
  2. The teaching method definitely does not work
  3. The result proves the method is effective
  4. The observed difference could plausibly be due to chance Correct answer.

Explanation

Statistical significance indicates whether an observed difference is unlikely to have arisen by chance. A non-significant result means the difference could plausibly be due to random variation, not that the method is proven ineffective. It may warrant further study with larger samples.

Question 25Scientific Inquiry and Experimental Design

Which statement correctly distinguishes an observation from an inference?

  1. An observation is gathered through the senses, while an inference is a logical interpretation. Correct answer.
  2. An observation is a prediction, while an inference is a measurement.
  3. An observation is an opinion, while an inference is a fact.
  4. An observation is always numerical, while an inference is always descriptive.

Explanation

An observation is information obtained directly through the senses or instruments, such as noting that a plant is wilted. An inference is a conclusion or interpretation drawn from observations, such as concluding the plant needs water. Keeping these distinct is central to sound scientific reasoning.

Question 26Scientific Inquiry and Experimental Design

In an experiment testing how fertilizer concentration affects plant height, which variable is the independent variable?

  1. The concentration of fertilizer Correct answer.
  2. The type of soil used
  3. The height of the plants
  4. The amount of water given

Explanation

The independent variable is the factor that the experimenter deliberately changes or manipulates. In this experiment, the concentration of fertilizer is varied to observe its effect, so it is the independent variable. Plant height is the dependent variable, and water and soil are controlled variables.

Question 27Scientific Inquiry and Experimental Design

A student measures the mass of a sample three times and obtains 10.2 g, 10.1 g, and 10.3 g. The true mass is 10.0 g. Which statement best describes the measurements?

  1. They are precise but not accurate. Correct answer.
  2. They are neither accurate nor precise.
  3. They are both accurate and precise.
  4. They are accurate but not precise.

Explanation

Precision refers to how close repeated measurements are to each other, while accuracy refers to how close a measurement is to the true value. Here, the three measurements are close to each other (high precision) but their average (10.2 g) is not close to the true mass (10.0 g), so they are not accurate. Thus, the measurements are precise but not accurate.

Question 28Scientific Inquiry and Experimental Design

A scientist wants to test the effect of temperature on the rate of enzyme activity. Which of the following is the most appropriate control group?

  1. A test tube with enzyme and substrate at a range of temperatures.
  2. A test tube with enzyme and substrate at the optimal temperature.
  3. A test tube with enzyme and substrate at a fixed temperature, such as 25°C. Correct answer.
  4. A test tube with substrate only, without enzyme, at the same temperatures.

Explanation

A control group is used as a baseline for comparison and should be kept under standard or constant conditions while the experimental groups vary the independent variable. In this experiment, the independent variable is temperature, so the control should be at a fixed, standard temperature (e.g., 25°C) to compare the effects of other temperatures. The other options either vary temperature or omit a key component, and thus do not serve as a proper control for temperature effects.

Question 29Scientific Inquiry and Experimental Design

A researcher reports a correlation coefficient of -0.85 between hours of study and number of errors on a test. Which conclusion is most justified?

  1. Studying more hours causes fewer errors.
  2. Most students who studied more made more errors.
  3. There is a strong negative association between study hours and errors. Correct answer.
  4. The relationship is weak and not meaningful.

Explanation

A correlation coefficient of -0.85 indicates a strong negative linear relationship: as one variable increases, the other tends to decrease. However, correlation does not imply causation, so we cannot conclude that studying causes fewer errors. The most justified conclusion is that there is a strong negative association between the two variables.

Question 30Scientific Inquiry and Experimental Design

A student measures the volume of a liquid using a graduated cylinder with 1 mL markings. The liquid level is between 43 mL and 44 mL. How should the student report the measurement with the correct number of significant figures?

  1. 43.5 mL Correct answer.
  2. 44 mL
  3. 43 mL
  4. 43.50 mL

Explanation

When using an analog scale, the measurement should be estimated to one decimal place beyond the smallest marked division. Since the cylinder has markings every 1 mL, the student can estimate to the nearest 0.1 mL, giving a reading like 43.5 mL. Reporting 43 mL or 44 mL would not reflect the estimation, and 43.50 mL implies precision to 0.01 mL, which is not justified.

Question 31Measurement, Units, and Data Analysis

A student records the length of a metal rod as 12.40 cm. How many significant figures does this measurement contain?

  1. 3
  2. 4 Correct answer.
  3. 2
  4. 5

Explanation

All non-zero digits count, and a trailing zero after a decimal point is significant. The digits 1, 2, 4, and the trailing 0 all count, giving four significant figures.

Question 32Measurement, Units, and Data Analysis

Which SI base unit is used to express the amount of a substance in the International System of Units?

  1. kelvin
  2. candela
  3. ampere
  4. mole Correct answer.

Explanation

The mole is the SI base unit for amount of substance, defined via the fixed Avogadro constant. Kelvin measures thermodynamic temperature, candela luminous intensity, and ampere electric current.

Question 33Measurement, Units, and Data Analysis

A laboratory balance reads 0.05020 kg. Expressed in grams, what is this mass written in scientific notation?

  1. 5.020 × 10⁻² g
  2. 5.020 × 10¹ g Correct answer.
  3. 5.020 × 10⁰ g
  4. 5.020 × 10² g

Explanation

Multiplying by 1000 converts kilograms to grams, giving 50.20 g. In scientific notation this is 5.020 × 10¹ g, preserving all four significant figures.

Question 34Measurement, Units, and Data Analysis

A set of repeated measurements clusters tightly around a value that is 2.0 cm away from the accepted true value. Which statement best describes this data set?

  1. It is both accurate and precise
  2. It is precise but not accurate Correct answer.
  3. It is neither accurate nor precise
  4. It is accurate but not precise

Explanation

Precision describes how closely repeated measurements agree with each other, while accuracy describes closeness to the true value. Tight clustering shows high precision, and the 2.0 cm offset from the true value shows low accuracy.

Question 35Measurement, Units, and Data Analysis

A student measures the mass of a sample three times and obtains 4.52 g, 4.51 g, and 4.53 g. What is the mean mass reported to the correct number of decimal places?

  1. 4.520 g
  2. 4.52 g Correct answer.
  3. 4.53 g
  4. 4.5 g

Explanation

The mean is (4.52 + 4.51 + 4.53)/3 = 13.56/3 = 4.52 g. The mean should be reported to the same decimal place as the input data, which is two decimal places.

Question 36Measurement, Units, and Data Analysis

Which quantity is classified as a derived quantity rather than an SI base quantity?

  1. temperature
  2. mass
  3. density Correct answer.
  4. time

Explanation

Density is defined as mass divided by volume, so it is built from base quantities and is therefore derived. Mass, time, and thermodynamic temperature are all SI base quantities.

Question 37Measurement, Units, and Data Analysis

A rectangular block has a measured volume of 25.0 cm³ and a mass of 197.5 g. What is its density, reported to the appropriate number of significant figures?

  1. 7.900 g/cm³
  2. 7.9 g/cm³
  3. 7.90 g/cm³ Correct answer.
  4. 8 g/cm³

Explanation

Density equals mass divided by volume: 197.5/25.0 = 7.90 g/cm³. Because the volume has three significant figures, the result is limited to three significant figures, giving 7.90.

Question 38Measurement, Units, and Data Analysis

A car travels 150 km in 2.0 hours. What is its average speed expressed in SI base units?

  1. 75 m/s
  2. 1500 m/s
  3. 0.021 m/s
  4. 21 m/s Correct answer.

Explanation

Average speed is 150 km / 2.0 h = 75 km/h. Converting, 75 km/h × (1000 m / 1 km) × (1 h / 3600 s) ≈ 20.8 m/s, which rounds to 21 m/s.

Question 39Measurement, Units, and Data Analysis

A data table lists temperatures recorded at fixed one-hour intervals. Which type of graph is most appropriate for displaying how temperature changes with time?

  1. A pie chart divided by temperature range
  2. A bar chart with separate bars for each temperature
  3. A scatter plot with no connecting line or axis label
  4. A line graph with time on the horizontal axis Correct answer.

Explanation

Continuous change of one variable with another is best shown on a line graph, with the independent variable (time) on the horizontal axis. Pie and bar charts suit categorical comparisons, not continuous trends.

Question 40Measurement, Units, and Data Analysis

A student measures the same 10.00 mL volume five times and obtains readings of 10.02, 10.03, 10.01, 10.02, and 10.02 mL. Which statement about the measurements is best supported?

  1. The readings are inaccurate because each differs from 10.00 mL
  2. The readings are precise because they agree closely with one another Correct answer.
  3. The readings cannot be assessed without knowing the true volume
  4. The readings are imprecise because they vary by 0.02 mL

Explanation

Precision refers to the mutual agreement of repeated measurements. These readings all fall within 0.02 mL of each other, indicating high precision regardless of closeness to a true value.

Question 41Measurement, Units, and Data Analysis

A sample's length is reported as 3.6 m. Which statement correctly interprets the uncertainty implied by this reported value?

  1. The last digit is uncertain, so the true length lies near 3.6 m within about ±0.05 m Correct answer.
  2. The value implies an uncertainty of ±0.5 m
  3. The value has four significant figures
  4. The length is exact to the nearest micrometre

Explanation

In a reported measurement, the final digit carries the uncertainty. For 3.6 m, the last place is the tenths, so the uncertainty is roughly half of that place, about ±0.05 m.

Question 42Measurement, Units, and Data Analysis

A graph of distance against time for a moving object gives a straight line through the origin. What does the slope of this line represent?

  1. The total distance travelled
  2. The time taken to travel one metre
  3. The speed of the object Correct answer.
  4. The acceleration of the object

Explanation

Slope equals the change in the vertical quantity divided by the change in the horizontal quantity. For a distance–time graph this is distance divided by time, which is speed.

Question 43Measurement, Units, and Data Analysis

A thermometer reads 25.0 °C. What is this temperature on the Kelvin scale, reported consistently with the data?

  1. 248.2 K
  2. 273.2 K
  3. 298.2 K Correct answer.
  4. 25.0 K

Explanation

Kelvin temperature equals Celsius temperature plus 273.15. Adding 273.15 to 25.0 °C gives 298.15 K, which is reported as 298.2 K to match the one decimal place of the reading.

Question 44Measurement, Units, and Data Analysis

A set of measurements yields a mean of 50.0 units with a standard deviation of 1.5 units. Which statement best describes the meaning of the standard deviation here?

  1. It is the largest reading in the data set
  2. It is the number of measurements taken
  3. It indicates the typical spread of individual readings about the mean Correct answer.
  4. It is the difference between the mean and the true value

Explanation

The standard deviation quantifies how widely individual measurements are distributed around the mean. A value of 1.5 units means readings typically deviate by about that amount from 50.0.

Question 45Measurement, Units, and Data Analysis

A student converts a pressure of 2.0 atm into pascals using 1 atm = 101.3 kPa. Which result is correct?

  1. 2.03 × 10² Pa
  2. 2.03 × 10⁶ Pa
  3. 2.03 × 10³ Pa
  4. 2.03 × 10⁵ Pa Correct answer.

Explanation

Multiplying 2.0 atm by 101.3 kPa gives 202.6 kPa, and 1 kPa equals 1000 Pa, so the result is 202 600 Pa, or about 2.03 × 10⁵ Pa.

Question 46Measurement, Units, and Data Analysis

Four groups measure the same quantity and report values of 9.81, 9.79, 9.80, and 9.82 m/s². The accepted value is 9.81 m/s². Which conclusion is best supported?

  1. The data are neither accurate nor precise
  2. The data are both accurate and precise Correct answer.
  3. The data are precise but inaccurate
  4. The data are accurate but imprecise

Explanation

The four values lie within 0.03 m/s² of one another, showing high precision, and their mean of 9.805 m/s² is essentially the accepted 9.81 m/s², showing high accuracy. Both qualities are therefore supported.

Question 47Measurement, Units, and Data Analysis

A student adds two measured masses, 12.3 g and 1.456 g. Applying significant-figure rules for addition, what should the reported sum be?

  1. 13.8 g Correct answer.
  2. 13.76 g
  3. 14 g
  4. 13.756 g

Explanation

The raw sum is 13.756 g, but addition rules limit the result to the least precise decimal place among the addends. Since 12.3 g is known only to the tenths place, the sum must be rounded to 13.8 g.

Question 48Measurement, Units, and Data Analysis

A graph of velocity against time for an object is a straight line with a positive slope that does not pass through the origin. What does the area under this line between two times represent?

  1. The acceleration during that interval
  2. The displacement during that time interval Correct answer.
  3. The average speed over the interval
  4. The rate of change of acceleration

Explanation

On a velocity–time graph, the area beneath the line equals velocity multiplied by time, which is displacement. The slope, by contrast, gives acceleration.

Question 49Measurement, Units, and Data Analysis

A measurement is quoted as (5.00 ± 0.05) cm. A student calculates the area of a square with this side length. Which reported area best reflects propagation of the absolute uncertainty?

  1. (25.0 ± 0.05) cm²
  2. (25.0 ± 0.0025) cm²
  3. (25.0 ± 0.5) cm² Correct answer.
  4. (25 ± 5) cm²

Explanation

For a power relationship A = s², the relative uncertainty doubles: 0.05/5.00 = 1%, so the area uncertainty is about 2% of 25.0 cm², or 0.5 cm². The result is therefore (25.0 ± 0.5) cm².

Question 50Measurement, Units, and Data Analysis

Two students each measure a length. Student A reports 0.450 m and Student B reports 45.0 cm. Which statement about these two reported values is correct?

  1. They represent the same length with the same number of significant figures Correct answer.
  2. Student B's value has three significant figures while Student A's has four
  3. Student A's value is more precise because metres are larger units
  4. They represent different lengths because the units differ

Explanation

Converting 0.450 m to centimetres gives 45.0 cm, so the two reports describe the same length. Each contains three significant figures, since the leading zero in 0.450 m is not significant.