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FTCE Middle Grades Science 5-9 (004) study materials
FTCE Middle Grades Science 5-9 (004) study resources

FTCE Middle Grades Science 5-9 (004) practice questions

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Question 1Nature of Science

A student measures the mass of the same rock five times and obtains 24.9 g, 25.0 g, 25.1 g, 24.9 g, and 25.1 g. The accepted value is 28.0 g. Which statement best describes the student's measurements?

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

Explanation

Precision refers to how closely repeated measurements agree with one another, while accuracy refers to how close a measurement is to the accepted or true value. The five trials cluster tightly together, which shows high precision, but all of them are about 3 g below the accepted value of 28.0 g, which shows poor accuracy.

Question 2Nature of Science

In an experiment testing how light intensity affects the rate of photosynthesis in Elodea, which variable should be held constant?

  1. Water temperature Correct answer.
  2. Rate of oxygen bubble production
  3. Light intensity
  4. Number of bubbles per minute

Explanation

A controlled experiment changes only the independent variable (light intensity) and measures the dependent variable (bubble production rate). All other factors that could affect photosynthesis, such as water temperature and carbon dioxide concentration, must be held constant so that any change in results can be attributed to light intensity alone.

Question 3Nature of Science

Which statement is a testable scientific hypothesis rather than an opinion or an untestable claim?

  1. Every living thing has an invisible energy field
  2. Bean plants grown in red light will grow taller than bean plants grown in green light Correct answer.
  3. Red light is the most beautiful color for a greenhouse
  4. Plants probably prefer music to silence

Explanation

A scientific hypothesis must be an evidence-based prediction that can be tested through observation or experiment and potentially shown false. Comparing plant height under two specified light colors is measurable and falsifiable, whereas aesthetic judgments, vague preferences, and undetectable forces cannot be tested.

Question 4Nature of Science

A scientist reports that a new fertilizer increased tomato yield by 15 percent. Which additional information is most important for other scientists to evaluate the reliability of this conclusion?

  1. The brand name of the fertilizer used
  2. Whether the study included a control group and repeated trials Correct answer.
  3. The color of the tomatoes produced
  4. The scientist's personal opinion of the fertilizer

Explanation

Reliability of a causal claim depends on proper experimental design, including a control group for comparison and replication to reduce the influence of chance. Details such as brand, color, or opinion do not allow peers to judge whether the 15 percent gain was truly caused by the fertilizer.

Question 5Nature of Science

Which of the following best describes the role of peer review in the scientific process?

  1. Government agencies decide whether results support public policy
  2. The original author repeats the experiment until results agree
  3. Independent experts evaluate the methods and evidence before publication Correct answer.
  4. Journals select articles based on the popularity of the topic

Explanation

Peer review is a quality-control step in which qualified, independent scientists examine a manuscript's methods, data, and reasoning before it is published. It does not guarantee truth, but it filters out poorly supported or flawed work and helps maintain scientific standards.

Question 6Nature of Science

A student uses a graduated cylinder to measure 50.0 mL of water. The markings are every 1 mL. Which reading is recorded with the appropriate number of significant figures?

  1. 50.000 mL
  2. 50.00 mL
  3. 50.0 mL Correct answer.
  4. 50 mL

Explanation

When reading a graduated cylinder marked in 1 mL increments, a careful observer estimates one additional digit beyond the smallest marking. Recording 50.0 mL reflects that estimated tenth of a milliliter and is consistent with the precision of the instrument.

Question 7Nature of Science

A student claims that a plant grew 2 cm taller because it was watered with sugar water rather than plain water. Which statement identifies the strongest flaw in this claim if the student tested only one plant per treatment?

  1. Plant height is not a measurable variable
  2. The claim cannot be flawed because growth was observed
  3. Sugar water always kills plants, so growth is impossible
  4. A single plant per group cannot separate treatment effects from individual variation Correct answer.

Explanation

With only one plant in each treatment, any difference could be due to natural variation among individual plants rather than the type of water. Replication with multiple plants per group and random assignment would help separate the treatment effect from individual differences.

Question 8Nature of Science

A hypothesis is best described as which of the following?

  1. A random guess made without prior knowledge
  2. A final conclusion that ends an investigation
  3. A proposed, testable explanation for an observation Correct answer.
  4. A proven fact accepted by all scientists

Explanation

A hypothesis is a tentative, testable explanation or prediction based on prior observations and background knowledge. It guides investigation and can be supported, revised, or rejected as evidence accumulates.

Question 9Nature of Science

Which sequence correctly represents the general order of a scientific investigation?

  1. Hypothesis, conclusion, question, experiment, data analysis
  2. Experiment, question, conclusion, hypothesis, data analysis
  3. Question, hypothesis, experiment, data analysis, conclusion Correct answer.
  4. Conclusion, data analysis, hypothesis, question, experiment

Explanation

Scientific inquiry typically begins with a question, followed by a testable hypothesis, a planned experiment, analysis of the collected data, and a conclusion that evaluates the hypothesis. The process is flexible and may loop back, but this sequence reflects the standard logical order.

Question 10Nature of Science

A graph shows a strong positive correlation between hours of television watched and body mass index in a group of students. Which conclusion is best supported by this correlation?

  1. Increased body mass index causes students to watch television
  2. No relationship exists between the variables
  3. Watching television directly causes increased body mass index
  4. The two variables are associated, but causation is not established Correct answer.

Explanation

Correlation indicates that two variables vary together, but it does not by itself demonstrate that one causes the other. A third variable, such as diet or physical activity, could influence both, so only an association is supported without a controlled experiment.

Question 11Nature of Science

Which of the following is an example of qualitative data?

  1. The reaction took 45 seconds to complete
  2. The solution turned cloudy after the reactants were mixed Correct answer.
  3. The solution reached a temperature of 32 degrees Celsius
  4. The mass of the product was 4.2 grams

Explanation

Qualitative data are descriptive observations that do not involve numerical measurement, such as a color change or cloudiness. Temperature, mass, and time are all expressed as numbers and are therefore quantitative data.

Question 12Nature of Science

A student wants to determine whether a new type of battery lasts longer than a standard battery. Which procedure would best test this question?

  1. Test one new battery and one standard battery once
  2. Run several batteries of each type under identical conditions and compare average operating times Correct answer.
  3. Measure the physical size of each battery type
  4. Ask classmates which battery they think lasts longer

Explanation

A valid comparison requires multiple trials of each battery type tested under identical conditions so that average performance can be compared while controlling other variables. Repeated trials reduce the influence of chance and individual battery variation.

Question 13Nature of Science

Which statement best explains why scientific explanations are considered open to revision?

  1. Older explanations are always completely wrong
  2. New evidence or improved methods can require existing explanations to be modified Correct answer.
  3. Scientific knowledge is based only on personal beliefs
  4. Scientists are required by law to change conclusions every year

Explanation

Science is self-correcting: as new data, technologies, or analyses become available, explanations are reexamined and revised when the evidence warrants it. This does not mean prior explanations were worthless, only that conclusions remain provisional and evidence-based.

Question 14Nature of Science

A student measures the length of a metal rod as 12.4 cm, 12.3 cm, and 12.5 cm. Which value is the best estimate of the true length?

  1. 12.0 cm
  2. 12.3 cm
  3. 12.4 cm Correct answer.
  4. 13.0 cm

Explanation

The best estimate from repeated measurements is the mean, which here is (12.4 + 12.3 + 12.5) / 3 = 12.4 cm. Averaging reduces the effect of random error in individual readings.

Question 15Nature of Science

A controlled experiment is designed to test the effect of temperature on the solubility of a salt. Which is the independent variable?

  1. Temperature of the water Correct answer.
  2. Time allowed for stirring
  3. Amount of salt that dissolves
  4. Volume of water used

Explanation

The independent variable is the factor deliberately changed by the investigator, which in this experiment is the water temperature. The dependent variable is the amount of salt that dissolves, and the volume of water and stirring time are controlled variables.

Question 16Nature of Science

Which of the following best describes the purpose of a control group in an experiment?

  1. It provides a baseline for comparison without the treatment being tested Correct answer.
  2. It replaces the need for repeated trials
  3. It guarantees the hypothesis will be supported
  4. It increases the number of variables being tested

Explanation

A control group is treated the same as the experimental group except that it does not receive the independent variable. This provides a baseline against which the effect of the treatment can be measured and helps rule out alternative explanations.

Question 17Nature of Science

A model of the solar system predicts that a certain planet will be visible at a specific location on a given night. Astronomers observe the planet there. What does this observation demonstrate about the model?

  1. The model has predictive validity for this case Correct answer.
  2. The observation has no bearing on the model
  3. The model is proven completely correct in every respect
  4. The model is invalid because it is only a model

Explanation

A model gains support when its predictions are confirmed by observation, demonstrating predictive validity for the tested case. Confirmation strengthens confidence but does not prove a model correct in every detail, since future evidence could reveal limitations.

Question 18Nature of Science

A scientist repeats an experiment and obtains results that contradict the original findings. What is the most appropriate scientific response?

  1. Investigate the discrepancy by reviewing methods and gathering more data Correct answer.
  2. Conclude immediately that all science is unreliable
  3. Change the data to match the original results
  4. Ignore the new results because the original study was published

Explanation

Contradictory results are an opportunity to examine procedures, identify sources of error, and collect additional evidence. Science progresses by resolving discrepancies through careful investigation rather than by ignoring or altering data.

Question 19Nature of Science

Which measurement has the greatest number of significant figures?

  1. 450 m
  2. 0.0045 m
  3. 0.00450 m Correct answer.
  4. 4.5 m

Explanation

In 0.00450 m, the leading zeros are not significant, but the trailing zero after the 5 is significant, giving three significant figures. The other values have only two significant figures each.

Question 20Nature of Science

A student graphs data from an experiment and finds that the points fall along a straight line that does not pass through the origin. Which relationship do the data suggest?

  1. No relationship between the variables
  2. A linear relationship with a nonzero y-intercept Correct answer.
  3. A direct proportion passing through the origin
  4. An inverse relationship between the variables

Explanation

A straight-line graph indicates a linear relationship, and a line that does not pass through the origin has a nonzero y-intercept. A direct proportion would require the line to pass through the origin, and an inverse relationship would produce a curved graph.

Question 21Nature of Science

Which of the following is the best example of a scientific theory?

  1. A guess a student makes before an experiment
  2. The theory of plate tectonics, supported by multiple lines of evidence Correct answer.
  3. A single observation recorded in a notebook
  4. An opinion shared by most people in a community

Explanation

In science, a theory is a well-substantiated explanation of natural phenomena that is supported by extensive evidence and has survived repeated testing. Plate tectonics fits this definition, whereas guesses, opinions, and single observations do not.

Question 22Nature of Science

Two groups of students test the same hypothesis using different methods and obtain the same conclusion. What does this outcome most strongly suggest?

  1. The hypothesis has been proven beyond any possible doubt
  2. The conclusion is invalid because the methods differed
  3. The conclusion is robust because it is supported by independent lines of evidence Correct answer.
  4. The students must have copied each other's methods

Explanation

When independent investigations using different methods converge on the same conclusion, confidence in that conclusion increases because the result is unlikely to be an artifact of one particular procedure. Convergence strengthens support but still does not constitute absolute proof.

Question 23Nature of Science

A researcher finds that a drug reduces symptoms in 70 percent of patients in a trial, but the trial had no placebo group. Which is the most significant limitation of the study?

  1. Without a placebo group, improvement cannot be clearly attributed to the drug Correct answer.
  2. Drug trials should never involve patients
  3. The 70 percent figure is too high to be believable
  4. Symptoms cannot be measured in patients

Explanation

A placebo group controls for expectation effects and natural recovery, so without one the observed improvement could result from factors other than the drug. This weakens any causal claim about the drug's effectiveness.

Question 24Nature of Science

A scientist proposes that a new particle exists but the particle can never be detected by any conceivable instrument. How does this proposal conflict with the nature of scientific hypotheses?

  1. Scientific claims must be approved by a majority of scientists
  2. A scientific claim must be testable through observation or experiment Correct answer.
  3. Scientific claims must be supported by government funding
  4. Scientific claims must be expressed mathematically

Explanation

Scientific hypotheses must be empirically testable, meaning there must be some possible observation that could support or refute them. A claim that is undetectable in principle cannot be tested, so it falls outside the scope of empirical science.

Question 25Nature of Science

A student concludes that a fertilizer caused greater plant growth because the fertilized plants were also placed in a sunnier window. Which error in experimental design has the student made?

  1. Too many repeated trials were performed
  2. Confounding variables were not controlled Correct answer.
  3. The hypothesis was not stated
  4. The dependent variable was not measured

Explanation

Because light exposure differed between the groups along with the fertilizer treatment, the effect of the fertilizer cannot be separated from the effect of sunlight. Such uncontrolled confounding variables undermine the validity of causal conclusions.

Question 26Nature of Science

A student measures the mass of a sample three times and obtains 5.02 g, 5.01 g, and 5.03 g. The accepted value is 5.50 g. Which statement correctly describes the student's measurements?

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

Explanation

Precision refers to how closely repeated measurements agree with one another, while accuracy refers to how close a measurement is to the true or accepted value. The three masses are tightly clustered, indicating high precision, but they are all about 0.48 g below the accepted value, indicating low accuracy.

Question 27Nature of Science

In a scientific investigation, what is the primary role of a hypothesis?

  1. To summarize the final conclusions drawn from an experiment.
  2. To describe a widely accepted explanation supported by extensive evidence.
  3. To serve as a step-by-step procedure for conducting the experiment.
  4. To provide a testable prediction that can be supported or refuted by evidence. Correct answer.

Explanation

A hypothesis is a proposed explanation or prediction that must be testable through observation or experiment. It guides the investigation and can be supported or contradicted by the resulting data.

Question 28Nature of Science

A student wants to determine whether a new fertilizer increases tomato plant height. Which procedure would best test this hypothesis?

  1. Measure the height of plants that have already been fertilized and compare to the average height of all tomato plants.
  2. Grow one group of plants with fertilizer and another identical group without fertilizer, keeping all other conditions the same. Correct answer.
  3. Grow plants with fertilizer and compare their height to plants grown in a different type of soil.
  4. Add fertilizer to all plants and measure their height daily for two weeks.

Explanation

A controlled experiment requires an experimental group that receives the treatment and a control group that does not, while all other variables are held constant. This allows the effect of the fertilizer to be isolated. The other options fail to control variables or lack a proper comparison group.

Question 29Nature of Science

A student records the following observations during an experiment: the solution turned from clear to blue, the temperature rose from 22°C to 35°C, and bubbles formed rapidly. Which statement best classifies these data?

  1. The color change and bubble formation are qualitative; the temperature change is quantitative. Correct answer.
  2. The color change is quantitative; the temperature change and bubble formation are qualitative.
  3. All three observations are qualitative because they describe the senses.
  4. All three observations are quantitative because they involve measurements.

Explanation

Qualitative data describe qualities or characteristics that are observed but not measured numerically, such as color and bubble formation. Quantitative data involve numerical measurements, such as the temperature change from 22°C to 35°C.

Question 30Nature of Science

A graph shows a strong positive correlation between hours of television watched and body mass index (BMI) in a group of students. Which conclusion is most justified?

  1. Watching television causes an increase in BMI.
  2. Increased BMI causes students to watch more television.
  3. There is an association between television watching and BMI, but causation cannot be established from this study. Correct answer.
  4. The correlation proves that television watching has no effect on BMI.

Explanation

Correlation indicates a relationship between two variables but does not by itself demonstrate that one variable causes the other. Other factors, such as diet or physical activity, could influence both television watching and BMI. Therefore, only an association can be concluded.

Question 31Nature of Science

A controlled experiment is designed to test the effect of temperature on the solubility of a salt. Which factor is the independent variable?

  1. The type of salt used.
  2. The amount of salt that dissolves.
  3. The volume of water used.
  4. The temperature of the water. Correct answer.

Explanation

The independent variable is the factor that the experimenter deliberately changes. In this experiment, temperature is being varied to observe its effect, so it is the independent variable. The amount of salt that dissolves is the dependent variable, and the other factors are controlled variables.

Question 32Nature of Science

A model of the solar system predicts that a certain planet will be visible at a specific location on a given night. Astronomers observe the planet at that location. What does this observation most directly demonstrate?

  1. The model is invalid because it is only a representation.
  2. The model has predictive power and is supported by the observation. Correct answer.
  3. The model is a proven fact that cannot be changed.
  4. The model is the only possible explanation for the planet's position.

Explanation

A scientific model is valuable when it can make accurate predictions that are confirmed by observation. This successful prediction supports the model's validity, though it does not prove the model is the only possible explanation.

Question 33Nature of Science

A scientist repeats an experiment and obtains results that contradict the original findings. What is the most appropriate next step?

  1. Report the new results and investigate possible sources of the discrepancy. Correct answer.
  2. Conclude that the original experiment was fraudulent.
  3. Average the two sets of results without further investigation.
  4. Ignore the new results because the original experiment was already published.

Explanation

In science, contradictory results must be taken seriously and investigated. The scientist should report the new findings and examine variables such as differences in methods, materials, or conditions that might explain the discrepancy.

Question 34Nature of Science

A team of middle school science students wants to know whether a new type of paper towel absorbs more water than the brand currently used in class. Which step should the team take first to investigate this question scientifically?

  1. Write a conclusion explaining which towel is better.
  2. State a testable hypothesis that predicts how the two towels will compare. Correct answer.
  3. Record the mass of water absorbed by each towel.
  4. Repeat the trial several times to confirm the results.

Explanation

Scientific inquiry generally begins with a question and a testable hypothesis that predicts an outcome before data are collected. Measuring, repeating trials, and drawing conclusions all come later in the process. Without a stated prediction, the students have no defined basis for deciding what to measure or how to interpret results.

Question 35Nature of Science

A student claims that a certain vitamin supplement improves memory. To test this claim in a middle school science investigation, which design would best control for the placebo effect?

  1. Give the supplement to one group and no pill at all to a second group, and tell both groups which treatment they received.
  2. Give the supplement to the students who volunteer and compare them with students who do not volunteer.
  3. Give the supplement to all students and compare their memory scores before and after taking it.
  4. Give the supplement to one group and a pill with no active ingredient to a second group, with neither group told which pill they received. Correct answer.

Explanation

A placebo control uses an inactive treatment so that both groups share the same expectation of receiving a pill, and blinding keeps that expectation from influencing reported results. Comparing an active pill with no pill leaves differences in expectation and routine uncontrolled. This design isolates the effect of the supplement itself rather than the belief that one is being helped.

Question 36Nature of Science

A student plots data from an experiment and finds that the relationship between the manipulated variable and the responding variable is curved rather than straight. The student's teacher says the pattern suggests a nonlinear relationship. Which statement best describes how the student should interpret and communicate this result?

  1. The student should connect the points with a straight line and report a constant rate of change.
  2. The student should conclude that the experiment failed and that no relationship exists.
  3. The student should describe the curve, consider a nonlinear model, and report that the relationship is not proportional. Correct answer.
  4. The student should discard the curved points because scientific relationships must be linear.

Explanation

Data that produce a curve indicate that the responding variable does not change at a constant rate with the manipulated variable, so a nonlinear model should be considered and the finding reported accurately. Curved patterns are legitimate scientific results, not errors to be removed or hidden. Describing the shape of the graph communicates the relationship honestly to others.

Question 37Physical Science

A student measures the mass of a metal cube as 54.0 g and its volume as 20.0 cm³. What is the density of the metal?

  1. 0.370 g/cm³
  2. 2.70 g/cm³ Correct answer.
  3. 74.0 g/cm³
  4. 1080 g/cm³

Explanation

Density equals mass divided by volume, so 54.0 g ÷ 20.0 cm³ = 2.70 g/cm³. The result carries three significant figures, matching the given measurements. This value is consistent with aluminum.

Question 38Physical Science

Which observation provides the best evidence that a chemical change has occurred rather than a physical change?

  1. A piece of metal is hammered into a thin sheet.
  2. A colorless gas is produced that turns limewater cloudy. Correct answer.
  3. A liquid is heated and begins to boil.
  4. A solid dissolves in water and the mixture becomes clear.

Explanation

A new substance forming is the hallmark of a chemical change, and carbon dioxide turning limewater cloudy indicates a new product. Dissolving, boiling, and hammering alter form or state but not chemical identity. Only the gas production signals a reaction.

Question 39Physical Science

According to Newton's third law, which statement describes the forces between a swimmer and the water during a push-off?

  1. The swimmer's push and the water's push cancel, so no acceleration occurs.
  2. The swimmer pushes the water backward, and the water pushes the swimmer forward with an equal force. Correct answer.
  3. The swimmer pushes the water forward, and the water pushes the swimmer forward.
  4. The water pushes the swimmer forward with a larger force than the swimmer exerts.

Explanation

Newton's third law states that forces occur in equal and opposite pairs acting on different objects. The swimmer's backward push on the water is matched by a forward push of the water on the swimmer, which accelerates the swimmer forward. The paired forces act on different bodies, so they do not cancel.

Question 40Physical Science

Which subatomic particles determine the atomic number of an element?

  1. Electrons in the outer shell
  2. Protons only Correct answer.
  3. Protons and neutrons together
  4. Neutrons only

Explanation

The atomic number is defined as the number of protons in the nucleus, which uniquely identifies the element. Neutrons affect mass number and isotopes, and electrons affect charge and bonding but not identity. Therefore only protons define atomic number.

Question 41Physical Science

Which statement correctly distinguishes a single replacement reaction from a double replacement reaction?

  1. In a single replacement, one element displaces another in a compound, while in a double replacement two ionic compounds exchange partners. Correct answer.
  2. In a single replacement, a compound breaks into elements, while in a double replacement two elements combine.
  3. In a single replacement, two elements form one compound, while in a double replacement one element displaces another.
  4. In a single replacement, two compounds combine, while in a double replacement one compound breaks apart.

Explanation

A single replacement follows the pattern A + BC → AC + B, where one element displaces another in a compound. A double replacement follows AB + CD → AD + CB, in which ions exchange partners, often forming a precipitate. Recognizing these patterns helps predict products.

Question 42Physical Science

A 4.0 kg cart moving at 3.0 m/s collides with and sticks to a 2.0 kg cart initially at rest. What is the velocity of the combined carts after the collision?

  1. 3.0 m/s
  2. 2.0 m/s Correct answer.
  3. 6.0 m/s
  4. 1.0 m/s

Explanation

In a perfectly inelastic collision, momentum is conserved: (4.0 kg)(3.0 m/s) = (6.0 kg)v. Solving gives v = 12 kg·m/s ÷ 6.0 kg = 2.0 m/s. Kinetic energy is not conserved here, but momentum is.

Question 43Physical Science

Which change would increase the rate at which a solid reacts with an acid?

  1. Using larger pieces of the solid
  2. Cooling the acid solution
  3. Reducing the surface area of the solid
  4. Increasing the concentration of the acid Correct answer.

Explanation

Reaction rate rises with more frequent collisions between reactant particles. Higher acid concentration increases the number of collisions per unit time. Cooling, larger pieces, and less surface area all slow the reaction.

Question 44Physical Science

An object is placed 30 cm from a converging lens with a focal length of 10 cm. Where does the image form?

  1. 30 cm on the same side as the object
  2. 15 cm on the opposite side of the lens Correct answer.
  3. 45 cm on the opposite side of the lens
  4. 10 cm on the same side as the object

Explanation

Using the thin-lens equation 1/f = 1/do + 1/di: 1/10 = 1/30 + 1/di, so 1/di = 1/10 − 1/30 = 2/30. Thus di = 15 cm, and a positive value means a real image on the opposite side.

Question 45Physical Science

Which statement best explains why ionic compounds conduct electricity when molten but not when solid?

  1. In the solid state, ions are free to move, but melting traps them.
  2. In the solid state, ions are locked in a lattice, but melting frees them to move. Correct answer.
  3. Melting breaks the ionic bonds into neutral atoms that carry current.
  4. Melting produces free electrons that move through the liquid.

Explanation

Conduction requires mobile charged particles. In a solid ionic lattice, ions are fixed in place and cannot carry current, but melting allows ions to move freely. The charge carriers are ions, not electrons or neutral atoms.

Question 46Physical Science

A wave has a frequency of 250 Hz and a wavelength of 1.4 m. What is its speed?

  1. 180 m/s
  2. 251 m/s
  3. 350 m/s Correct answer.
  4. 0.0056 m/s

Explanation

Wave speed equals frequency multiplied by wavelength: v = fλ = 250 Hz × 1.4 m = 350 m/s. Frequency is cycles per second, so the product gives meters per second.

Question 47Physical Science

Which sequence correctly orders the steps of the scientific method as typically applied in a physical science investigation?

  1. Analyze data, form a hypothesis, state a question, conduct an experiment
  2. Conduct an experiment, state a question, analyze data, form a hypothesis
  3. State a question, form a hypothesis, conduct an experiment, analyze data Correct answer.
  4. Form a hypothesis, state a question, analyze data, conduct an experiment

Explanation

Scientific inquiry generally begins with a question, followed by a testable hypothesis, a controlled experiment, and analysis of results. Data analysis comes after data collection. The other sequences place analysis or experimentation before the question is even posed.

Question 48Physical Science

Which of the following best describes the difference between an element and a compound?

  1. An element contains only one type of atom, while a compound contains two or more elements chemically combined. Correct answer.
  2. An element is always a metal, while a compound is always a gas.
  3. An element can be separated by physical means, while a compound cannot.
  4. A compound contains only one type of atom, while an element contains two or more.

Explanation

An element consists of a single kind of atom and cannot be broken down chemically. A compound is a substance formed when two or more elements bond in fixed proportions. Elements include nonmetals and gases, so they are not always metals.

Question 49Physical Science

A 10-ohm resistor carries a current of 2 A. What is the voltage across the resistor, and how much power does it dissipate?

  1. 12 V and 24 W
  2. 5 V and 10 W
  3. 0.2 V and 0.4 W
  4. 20 V and 40 W Correct answer.

Explanation

Ohm's law gives V = IR = 2 A × 10 Ω = 20 V. Power is P = IV = 2 A × 20 V = 40 W, equivalently I²R. The other values arise from incorrect operations on the given numbers.

Question 50Physical Science

Which process releases energy when it occurs between two atoms?

  1. Melting a solid
  2. Forming a chemical bond Correct answer.
  3. Vaporizing a liquid
  4. Breaking a chemical bond

Explanation

Forming a bond lowers the potential energy of the system, releasing energy to the surroundings. Breaking a bond requires energy input. Melting and vaporizing are endothermic phase changes that absorb energy.