which of the following is an example of a chemical change

ATI TEAS 7

TEAS 7 science practice

1. Which of the following is an example of a chemical change?

A. Dissolving sugar in water
B. Boiling water
C. Rusting iron
D. Crushing ice

Correct answer: C

Rationale: Rusting iron is an example of a chemical change because it involves a chemical reaction where iron reacts with oxygen in the presence of water to form iron oxide (rust). This reaction results in a change in the chemical composition of the iron, unlike dissolving sugar in water, boiling water, or crushing ice, which are physical changes. Dissolving sugar in water is a physical change as sugar molecules remain unchanged but disperse in water. Boiling water is also a physical change as water changes its state from liquid to gas due to heat. Crushing ice is a physical change as the solid ice changes its physical form without altering its chemical composition.

2. What is the path of oxygenated blood flow in our body?

A. From the heart directly to the brain
B. From the lungs to the left atrium, then to the left ventricle, and out through the aorta
C. From the body to the right atrium to the lungs
D. From the left atrium directly to the aorta

Correct answer: B

Rationale: Oxygenated blood flows from the lungs to the left atrium, then to the left ventricle, and is pumped out through the aorta to the body. This pathway ensures efficient oxygen delivery to the body's tissues and organs. Choice A is incorrect as oxygenated blood does not flow directly from the heart to the brain. Choice C is incorrect as it suggests a route from the body to the right atrium and then to the lungs, which is the pathway for deoxygenated blood. Choice D is incorrect as it describes a direct pathway from the left atrium to the aorta, skipping the left ventricle, which is essential for pumping blood to the body.

3. Which term refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint?

A. Isometric contraction
B. Eccentric contraction
C. Isotonic contraction
D. Concentric contraction

Correct answer: D

Rationale: Concentric contraction refers to the condition where a muscle shortens in length while generating force, leading to movement at a joint. This type of contraction is commonly associated with the lifting phase of an exercise where the muscle is actively shortening against resistance. Isometric contraction (Choice A) involves muscle contraction without a change in muscle length, Eccentric contraction (Choice B) involves the muscle lengthening while generating force, and Isotonic contraction (Choice C) refers to muscle contraction against a constant load with a change in muscle length.

4. Which of the following is NOT a recognized mode of natural selection?

A. Directional selection (favoring one extreme trait value on a spectrum)
B. Disruptive selection (favoring both extreme trait values on a spectrum)
C. Stabilizing selection (favoring the average trait value on a spectrum)
D. Sexual selection (selection based on mate choice that influences reproductive success)

Correct answer: D

Rationale: A) Directional selection is a recognized mode of natural selection where one extreme trait value on a spectrum is favored over others, leading to a shift in the average trait value over time. B) Disruptive selection is a recognized mode of natural selection where both extreme trait values on a spectrum are favored over the average trait value, potentially causing the population to split into distinct groups. C) Stabilizing selection is a recognized mode of natural selection favoring the average trait value on a spectrum over extreme values, resulting in reduced genetic diversity. D) Sexual selection differs from traditional natural selection modes as it involves mate choice and competition for mates, not direct selection pressure on traits affecting survival and reproduction in the environment. Sexual selection can drive the evolution of traits enhancing an individual's attractiveness for mating purposes.

5. What is the stoichiometric coefficient of nitrogen (N2) in the balanced equation for the Haber process: N2 + 3H2 → 2NH3?

A. 1
B. 2
C. 3
D. 4

Correct answer: A

Rationale: In the balanced equation for the Haber process: N2 + 3H2 → 2NH3, the stoichiometric coefficient of nitrogen (N2) is 1. This means that one molecule of nitrogen reacts with three molecules of hydrogen to produce two molecules of ammonia. The coefficient '1' indicates the mole ratio of N2 in the reaction. Choice B, 2, is incorrect because it represents the coefficient for ammonia (NH3) in the balanced equation. Choice C, 3, is incorrect as it corresponds to the coefficient of hydrogen (H2). Choice D, 4, is not the correct stoichiometric coefficient for nitrogen (N2) in this equation.