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Quiz: Science in the Kitchen

Test your understanding of the scientific method, lab safety, measurement, and foundational chemistry with these questions.

1. What is a hypothesis?

  1. A final conclusion supported by multiple experiments
  2. A specific, testable prediction that explains an observation
  3. A measurement recorded during an experiment
  4. A rule that keeps scientists safe in the lab
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The correct answer is B. A hypothesis is a specific, testable prediction — not a proven fact. It must be something you can actually check with an experiment. Option A describes a scientific theory or conclusion, not a hypothesis. Option C is a data point, and option D is a safety rule. A good hypothesis follows the "If…then…because" pattern.

Concept Tested: Hypothesis Formation

2. In an experiment testing how different amounts of sugar affect how high bread dough rises, what is the dependent variable?

  1. The brand of yeast used
  2. The amount of sugar added to each dough batch
  3. The height that the dough rises
  4. The oven temperature during baking
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The correct answer is C. The dependent variable is the outcome you measure — in this case, how high the dough rises. Option B is the independent variable (the one thing deliberately changed). Options A and D are controlled variables that are kept constant. The dependent variable "depends on" the change the experimenter makes.

Concept Tested: Variables in Experiments

3. Scientists worldwide use the metric system primarily because it

  1. Uses Fahrenheit for temperature measurement
  2. Is based on powers of ten and allows easy comparison of results globally
  3. Was invented by the United States government
  4. Only applies to measurements of mass and length
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The correct answer is B. The metric system (SI) is used universally in science because it is based on powers of ten, making calculations straightforward, and it ensures scientists in any country can compare data without converting units. Option A is incorrect — metric uses Celsius. Option C is false — it came from France. Option D is wrong — metric covers all measurement types including temperature, volume, and time.

Concept Tested: Metric System in Science

4. Which of the following is the best example of a controlled variable?

  1. The type of yeast used, kept identical across all experimental groups
  2. The rise height of the bread, measured after baking
  3. The amount of sugar added, which changes in each group
  4. The conclusion drawn from the data
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The correct answer is A. A controlled variable is something kept constant so it cannot affect the results. Option B is the dependent variable (the measured outcome). Option C is the independent variable (what is deliberately changed). Option D is not a variable at all but the final step of the scientific method.

Concept Tested: Controlled Experiment Design

5. A water molecule is described as "polar" because

  1. It contains only hydrogen and oxygen atoms
  2. It has an uneven distribution of charge, with a negative oxygen end and positive hydrogen ends
  3. It forms covalent bonds that are stronger than ionic bonds
  4. It dissolves only in acidic solutions
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The correct answer is B. Polarity means the molecule has opposite partial charges at different ends. In water, oxygen pulls electrons toward itself, giving it a slight negative charge (δ⁻) while the hydrogen ends carry slight positive charges (δ⁺). Option A just states the formula, which alone doesn't explain polarity. Option C describes bond strength, not polarity. Option D is incorrect — water dissolves many substances at all pH values.

Concept Tested: Water Molecule Structure

6. On the pH scale, a solution with pH 3 is how much more acidic than a solution with pH 5?

  1. Two times more acidic
  2. Five times more acidic
  3. One hundred times more acidic
  4. Twenty times more acidic
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The correct answer is C. The pH scale is logarithmic — each step of 1 represents a tenfold change. Moving from pH 5 to pH 4 is 10× more acidic; from pH 5 to pH 3 is 10 × 10 = 100 times more acidic. Option A would be true if the scale were linear. Options B and D are not consistent with the logarithmic nature of the pH scale.

Concept Tested: pH Scale

7. Which of the following is the BEST reason to run at least three trials in an experiment?

  1. To use more ingredients and reduce waste
  2. To satisfy a school grading requirement
  3. To reduce the chance that a single unusual result skews the conclusion
  4. To give more students a chance to participate
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The correct answer is C. Running multiple trials helps ensure results are consistent and not due to random chance. A single result might be a fluke; three consistent results provide more reliable evidence. Options A, B, and D describe non-scientific motivations unrelated to the purpose of replication in experimental design.

Concept Tested: Controlled Experiment Design

8. Which graph type is BEST suited for showing how a sourdough starter's height changes over 24 hours?

  1. Bar graph
  2. Pie chart
  3. Line graph
  4. Scatter plot
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The correct answer is C. A line graph is best for showing how something changes over time, making trends easy to see. A bar graph compares separate categories rather than tracking change over time. A pie chart shows parts of a whole. A scatter plot compares two measured variables without a direct time component, though it can be used for time data, it is less intuitive for continuous change over time.

Concept Tested: Graph and Data Interpretation

9. Which of the following foods is MOST acidic?

  1. Pure water (pH 7.0)
  2. Milk (pH 6.7)
  3. Egg whites (pH 9.0)
  4. Lemon juice (pH 2.0)
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The correct answer is D. The lower the pH number, the more acidic the solution. Lemon juice at pH 2.0 is the most acidic option listed. Pure water at pH 7 is neutral. Milk at pH 6.7 is slightly acidic. Egg whites at pH 9.0 are basic (alkaline), not acidic at all.

Concept Tested: pH Scale

10. What are the four major groups of molecules found in food?

  1. Protons, neutrons, electrons, and ions
  2. Carbohydrates, proteins, lipids, and water
  3. Acids, bases, salts, and buffers
  4. Carbon, hydrogen, oxygen, and nitrogen
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The correct answer is B. The four major food molecule groups are carbohydrates (sugars and starches), proteins, lipids (fats and oils), and water. Option A lists subatomic particles, not molecular groups. Option C lists chemical categories, not food molecule families. Option D lists the most common elements in food, not the molecular groups they form.

Concept Tested: Atoms and Molecules in Food