Laws Vs Theories
A scientist observes that a total mass is 50.0 g before and 50.0 g after a reaction. Is this an observation, theory, or law?
Observation: the statement reports measured evidence.
A scientists records "White pine trees have visible fungal growth on their bark." Observation or Inference?
Observation.
A balance gives 49.98 g, 50.02 g, and 50.01 g for an accepted value of 50 g. Accurate, precise, neither, or both?
In the nitrogen experiment, what is the independent variable? (from study guide; I'll go back and read it)
The amount/concentration of nitrogen fertilizer.
In a pond log, water depth changes from 45.2 cm to 22.8 cm. Is this quantitative or qualitative?
Quantitative.
Matter is neither created nor destroyed. This is because it describes what happens. The second one gives an explanation.
A student says "The trees are dying because soil acidity is too high." Why is this an inference?
The cause is being interpreted from the observation rather than being directly observed.
A balance gives 47.12 g, 47.11 g, and 47.13 g for an accepted value of 50.00 g. Accurate, precise, neither, or both?
In the nitrogen experiment, what is the dependent variable?
CO2, output/respiration rate measured over 24 hours.
What is the total decrease in water depth from April 12 to April 26th?
45.2 - 22.8 = 22.4 cm
Why would collecting more evidence not cause Dalton's Atomic Theory to "graduate" into the Law of Conservation of Mass?
They serve different purposes. A law describes a consistent relationship or pattern; a theory provides a broad, well-supported explanation. More evidence can strengthen it, but it cannot transform it.
Why is it scientifically dangerous to claim that soil acidity caused fungal growth based only on the pine-tree scenario?
The data show an association between soil acidity and the trees' condition, but do not isolate acidity as the cause. Other factors could contribute.
Balance C gives 48.50 g, 51.20 g, and 50.30 g, with an average of 50.00 g. Why can the average be accurate even though the individual measurements are not precise?
The average equals the accepted value, but the individual trails are widely spread apart.
Which statement is supported by the quantitative data: "Water temperature increased as water depth decreased" or "evaporation occurred at exactly 5 cm per week?"
No. Einsteins theory is an attempt to serve as a deeper explanation while Newton's Law describes gravitational relationships.
The field log days tadpoles were observed on April 23rd when water temperature was 19.5 degrees C. A student says, "The tadpoles appeared because the water reached 19.5 Degrees C." Identify the reasoning error.
The first statement is an observation; the second adds a causal explanation that is not directly supported by the log.
Using an accepted value of 50.00 g and an experimental value or 47.12 g, calculate percent error.
5.76%
The soap experiment compares hands before and after washing, but does not include an untouched or clean-hand control. Why does that weaken the experiment?
On April 19 the water was cloudy with green algae mats; on April 23 there was a strong odor and tadpoles near the surface. How can these qualitative observations add context to numerical data?
They provide descriptive context for what was happening in the pond as depth decreased and temperature increased, giving information that the numbers alone do not capture.
A student says: "Scientific Theories are weaker than laws because Theories can change." What is the best scientific response?
The reasoning is incorrect. Laws and theories have different purposes. A theory is a well-tested explanation; a law describes what scientists expect to happen under particular conditions. Neither is simply a "Higher level" of science.
Give one additional piece of evidence or experimental approach that would make the claim about soil acidity causing tree decline stronger.
Which balance most strongly suggests systematic error: A, B, C? Defend your answer.
B. Its measurements are very consistent but all are about 2.88 g below the accepted value.
Redesign the nitrogen experiment to test nitrogen's effect on respiration more validly. Name at least two changes.
Keep the temperature identical. Soil and water should also be kept the same.
A researcher finds the 100 mg nitrogen group has the lowest respiration rate and concludes, "High nitrogen inhibits respiration." Why can this conclusion not be considered definitive?
Because temperate differed between groups, temperature is confounded with nitrogen level. The study cannot determine whether nitrogen, temperature, or their combination caused the lower respiration rate.