1. A new material is claimed to be stronger than steel. You design an experiment to test this claim. What is the MOST important control variable?

A. The size of the material samples.
B. The temperature at which the test is conducted.
C. The force applied to the material.
D. The color of the material.

Correct answer: A

Rationale: The size of the material samples is the most important control variable because it ensures that the comparison between the new material and steel is fair and accurate. By keeping the size consistent, any differences in strength can be attributed to the material composition rather than variations in sample size. Controlling for size helps eliminate confounding variables and increases the reliability of the experiment results. Temperature, force applied, and color are not as critical for directly testing the strength comparison between the new material and steel.

2. Where does most of the chemical digestion and absorption of nutrients occur?

A. Mouth
B. Stomach
C. Small intestine
D. Large intestine

Correct answer: C

Rationale: Rationale: The small intestine is where most of the chemical digestion and absorption of nutrients occur in the digestive system. This is because the small intestine is lined with villi and microvilli, which increase the surface area available for absorption. Enzymes secreted by the pancreas and bile from the liver aid in breaking down food into smaller molecules that can be absorbed through the intestinal wall into the bloodstream. The stomach primarily functions in the mechanical breakdown of food and the initial stages of protein digestion, while the large intestine is mainly responsible for absorbing water and electrolytes from the remaining indigestible food particles. The mouth is involved in the initial mechanical breakdown of food through chewing and some chemical digestion of carbohydrates by salivary enzymes, but the majority of nutrient absorption occurs in the small intestine.

3. A balanced chemical equation for the reaction between sodium and chlorine to form sodium chloride is:

A. Na + Cl2 -> NaCl
B. 2Na + Cl2 -> 2NaCl
C. Na2 + Cl -> 2NaCl
D. Na + 2Cl -> NaCl2

Correct answer: A

Rationale: The correct balanced chemical equation for the reaction between sodium and chlorine to form sodium chloride is '2Na + Cl2 -> 2NaCl'. This equation is balanced as it shows that 2 atoms of sodium react with 1 molecule of chlorine gas to produce 2 molecules of sodium chloride. Option A 'Na + Cl2 -> NaCl' is incorrect as it does not balance the number of atoms on both sides of the equation. It only shows 1 atom of sodium reacting with 1 molecule of chlorine, which is not a balanced representation of the chemical reaction. Therefore, option B is the correct choice for this question.

4. Which term describes the resistance of a substance to flow?

A. Density
B. Viscosity
C. Conductivity
D. Malleability

Correct answer: b

Rationale: Viscosity refers to the resistance of a substance to flow. Substances with high viscosity flow slowly, while those with low viscosity flow more easily.

5. The phrase "illuminates not only past events" suggests that history

A. primarily serves as a nostalgic exercise in remembering old stories.
B. offers valuable lessons beyond simply recalling occurrences from the past.
C. is focused solely on factual accuracy and avoids drawing any interpretations.
D. exists only as a static record of unchanging events with no relevance to our lives.

Correct answer: B

Rationale: The phrase highlights that history goes beyond mere chronology, offering valuable insights and lessons beyond the dates and facts.