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How many times stronger is the hydrogen-ion concentration of a pH 4 solution compared with a pH 9 solution?
- A. 50
- B. 100,000
- C. 0.000001
- D. 5
Correct Answer: B
Rationale: The pH scale measures the concentration of hydrogen ions in a solution, where each pH unit change represents a tenfold difference in concentration. In this case, the pH 4 solution is 5 units lower than the pH 9 solution. Therefore, the difference of 5 pH units translates to a 10^5 times (or 100,000 times) increase in hydrogen-ion concentration in the pH 4 solution compared to the pH 9 solution. The pH scale is logarithmic, with each unit representing a tenfold change, so a 5-unit difference results in a 100,000-fold difference in hydrogen-ion concentration. Hence, option B, 100,000, is the correct answer.
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In a phase diagram, what term is used for a substance held at a temperature and pressure where solid, liquid, and gaseous states of a substance exist simultaneously?
- A. critical temperature
- B. triple point
- C. absolute zero
- D. critical point
Correct Answer: B
Rationale: The point described in the question is called the triple point. At the triple point, all three phases of a substance (solid, liquid, and gas) coexist in equilibrium. The critical temperature is the highest temperature at which a distinct liquid phase can form, while absolute zero is the lowest possible temperature. The critical point is the point on a phase diagram that represents the highest temperature and pressure at which a distinct liquid and gas phase can coexist. Therefore, the correct answer is the triple point, where all three phases coexist.
Use this information to answer the question A Mass (5.0g) Time of fall ( 2.0 sec). B mass( 5.0g) Time of fall (1.0sec) C mass (30.0g) Time of fall (0.5sec) D mass ( 35.0g ) Time of fall (1.5sec)
Which of the following is supported by the following data?
- A. Objects A and B will fall at the same rate.
- B. Air resistance is greater for A than for B.
- C. The time of fall is independent of the mass of the object.
- D. The greater the mass of an object, the faster it will fall.
Correct Answer: C
Rationale: The correct answer is C. The data provided shows different objects with varying masses falling for different durations. The observation that the time of fall varies with mass indicates that the time of fall is independent of the mass of the object, as seen from the given data. This supports the concept that in a vacuum or other situations where air resistance is negligible, objects of different masses will fall at the same rate, following the principle of gravitational acceleration acting equally on all objects regardless of their mass.
Which of the following proteins is present in blood plasma?
- A. Fibrinogen
- B. Lymphocytes
- C. Monocytes
- D. Platelets
Correct Answer: A
Rationale: The correct answer is A: Fibrinogen. Fibrinogen is a vital protein present in blood plasma that plays a key role in blood clotting. Lymphocytes, monocytes, and platelets are different types of blood cells and not proteins found in blood plasma. Understanding the components of blood plasma, such as fibrinogen, is essential for comprehending its functions in various physiological processes, particularly in clot formation.
Which of the following describes one difference between skeletal and cardiac muscles?
- A. Cardiac muscles are involuntary, whereas skeletal muscles are voluntary
- B. Skeletal muscles are not autorhythmic, whereas cardiac muscles are
- C. Skeletal muscles are found in the limbs, whereas cardiac muscles are found in the heart
- D. Skeletal muscles are not autorhythmic
Correct Answer: A
Rationale: The correct answer is A because cardiac muscles are involuntary, meaning they are not under conscious control, while skeletal muscles are voluntary, allowing conscious control over their movement. Option B is incorrect as skeletal muscles are not autorhythmic, unlike cardiac muscles. Option C is inaccurate as skeletal muscles are primarily found in the limbs, while cardiac muscles are predominantly located in the heart. Option D is false as skeletal muscles are not autorhythmic; instead, cardiac muscles possess autorhythmicity due to their ability to generate and conduct electrical impulses independently.
Which class of biological molecules includes enzymes?
- A. Carbohydrates
- B. Vitamins
- C. Lipids
- D. Proteins
Correct Answer: D
Rationale: Enzymes are proteins that serve as biological catalysts, accelerating chemical reactions in living organisms. Proteins, a class of biological molecules crucial for the structure and function of cells, tissues, and organs, include enzymes. While carbohydrates, vitamins, and lipids are essential biomolecules, they do not encompass enzymes. Therefore, the correct answer is Proteins (Choice D).