Nokea
When water boils, it changes from a liquid to a gas. This is an example of a:
- A. Chemical reaction
- B. Physical change
- C. Nuclear reaction
- D. Biological process
Correct Answer: B
Rationale: This is a physical change because boiling water involves a change in state from liquid to gas without altering the chemical composition of the water molecules. In a chemical reaction, new substances are formed by breaking and forming chemical bonds, which is not the case during boiling. A nuclear reaction involves changes in atomic nuclei, which are not occurring during boiling. A biological process refers to activities related to living organisms, which is not applicable to the change from liquid to gas in boiling water.
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How is power related to time?
- A. Power is inversely proportional to time
- B. Power is directly proportional to time
- C. Power is unrelated to time
- D. Power is the product of time and work
Correct Answer: C
Rationale: Power is a measure of how quickly work is done or energy is transferred. It is defined as the rate at which work is done or energy is transferred. Power is not directly or inversely proportional to time, as it depends on the amount of work done or energy transferred, not the duration over which it is done. The relationship between power and time is not a direct one, so power is unrelated to time. Choice A and B are incorrect because power's relationship with time is not one of direct or inverse proportionality. Choice D is incorrect because power is not simply the product of time and work; it is the rate at which work is done or energy is transferred, which can vary independently of time.
What is the formula to calculate work?
- A. Work = Force Distance
- B. Work = Mass Velocity
- C. Work = Power Time
- D. Work = Energy · Time
Correct Answer: A
Rationale: Work is defined as the product of the force applied to an object and the distance over which the force is applied. The formula to calculate work is represented by Work = Force Distance, where force is the applied force on an object and distance is the displacement over which the force is applied. Therefore, the correct formula to calculate work is Work = Force Distance.
Choice B, 'Work = Mass Velocity,' is incorrect because work involves force and distance, not mass and velocity. Choice C, 'Work = Power Time,' is incorrect because work is not directly calculated using power and time. Choice D, 'Work = Energy · Time,' is incorrect because work is not typically calculated by dividing energy by time; rather, it involves the product of force and distance.
The process by which two or more species reciprocally influence each other's evolution through selection pressures exerted on one another is called:
- A. Convergent evolution
- B. Divergent evolution
- C. Coevolution
- D. Coevolution
Correct Answer: C
Rationale: A) Convergent evolution refers to the process by which unrelated species evolve similar traits due to similar environmental pressures. This does not involve reciprocal influence between species.
B) Divergent evolution refers to the process by which two or more related species become more dissimilar over time due to different selection pressures. This also does not involve reciprocal influence between species.
C) Coevolution is the process by which two or more species reciprocally influence each other's evolution through selection pressures exerted on one another. This can lead to a close ecological relationship between the species, such as in predator-prey interactions or mutualistic relationships.
D) This option is a duplicate of option C.
What is the primary function of red blood cells in the cardiovascular system?
- A. To transport oxygen throughout the body.
- B. To fight infection and disease.
- C. To help regulate blood clotting.
- D. To remove waste products from the body.
Correct Answer: A
Rationale: Red blood cells, also known as erythrocytes, play a crucial role in the cardiovascular system by primarily transporting oxygen from the lungs to the body's tissues and organs. This essential function is carried out through the interaction of hemoglobin, a protein within red blood cells, which binds to oxygen in the lungs and releases it in the body's tissues. Choices B, C, and D are incorrect. Red blood cells are not actively involved in fighting infections, regulating blood clotting, or eliminating waste products from the body.
What is the formula for calculating molarity?
- A. M = n/V
- B. M = n/L
- C. M = mol/L
- D. M = mol/dm³
Correct Answer: A
Rationale: The correct formula for calculating molarity is M = n/V. In this formula, 'M' represents molarity, 'n' represents the number of moles of solute, and 'V' represents the volume of the solution in liters. Molarity is defined as the number of moles of solute per liter of solution, hence the ratio of moles to volume. Choice B, 'M = n/L', is incorrect because 'L' should represent liters instead of the number of moles. Choice C, 'M = mol/L', is incorrect as it does not include the representation of the number of moles 'n'. Choice D, 'M = mol/dm³', is incorrect because 'dm³' is a volume unit equal to a liter, but the correct representation should be in terms of the volume of the solution in liters. Therefore, the correct answer is M = n/V.