Nokea
Which of the following factors does NOT affect the rate of dissolution of a solute in a solvent?
- A. Temperature
- B. Pressure
- C. Surface area
- D. Particle size
Correct Answer: B
Rationale: Pressure does not affect the rate of dissolution of a solute in a solvent. The factors that affect the rate of dissolution include temperature, surface area, and particle size. Temperature generally increases the rate of dissolution by providing more energy for the solute particles to break apart and mix with the solvent. Increasing the surface area of the solute by grinding it into smaller particles or increasing its contact area with the solvent can also speed up dissolution. Similarly, reducing the particle size of the solute can increase the rate of dissolution by providing more surface area for interaction with the solvent. Pressure, however, does not have a significant impact on the dissolution process and is not a factor that influences the rate at which a solute dissolves in a solvent.
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The number of protons in an atom determines its:
- A. Mass number
- B. Atomic number
- C. Atomic weight
- D. Valence electron count
Correct Answer: B
Rationale: The number of protons in an atom is known as the atomic number. The atomic number uniquely identifies an element and determines its position on the periodic table. It is a fundamental property of an element and directly influences its chemical behavior and interactions. The mass number, on the other hand, is the sum of protons and neutrons in the nucleus of an atom, not just protons. Atomic weight is the average mass of an element's isotopes considering their relative abundance, not solely based on the number of protons. Valence electron count refers to the number of electrons in the outermost energy level of an atom, influencing its ability to form bonds and participate in chemical reactions, but it is not determined by the number of protons in the atom.
According to the wave theory of light, the bright fringes observed in a double-slit experiment correspond to:
- A. Constructive interference
- B. Destructive interference
- C. Increased diffraction
- D. Total internal reflection
Correct Answer: A
Rationale: In a double-slit experiment based on the wave theory of light, the bright fringes are the result of constructive interference. Constructive interference occurs when light waves from the two slits arrive at a point in phase, reinforcing each other and creating a bright fringe. This reinforcement leads to the constructive addition of the wave amplitudes, resulting in a bright spot on the screen. Destructive interference, which would result in dark fringes, occurs when waves are out of phase and cancel each other out. Increased diffraction and total internal reflection are not related to the formation of bright fringes in a double-slit experiment. Therefore, the correct answer is constructive interference.
What is the difference between emphysema and chronic bronchitis, both chronic obstructive pulmonary diseases (COPD)?
- A. Emphysema damages alveoli, while chronic bronchitis inflames airways.
- B. Emphysema causes coughing, while chronic bronchitis leads to shortness of breath.
- C. Emphysema is more reversible than chronic bronchitis.
- D. Emphysema affects only smokers, while chronic bronchitis can occur in non-smokers.
Correct Answer: A
Rationale: Emphysema is characterized by the destruction of alveoli in the lungs, leading to decreased surface area for gas exchange. Chronic bronchitis, on the other hand, involves inflammation and narrowing of the airways, leading to excessive mucus production and coughing. Therefore, the correct difference between emphysema and chronic bronchitis is that emphysema damages the alveoli, while chronic bronchitis inflames the airways. Choice B is incorrect because chronic bronchitis is associated with coughing, not emphysema. Choice C is incorrect as chronic bronchitis is typically less reversible compared to emphysema. Choice D is incorrect as both emphysema and chronic bronchitis are commonly seen in smokers, but chronic bronchitis can also occur in non-smokers due to other factors such as air pollution or genetic predisposition.
During exercise, heart rate increases to deliver more oxygen to the body's tissues. What other cardiovascular response also increases?
- A. Blood pressure decreases
- B. Blood vessel diameter narrows
- C. Blood flow to muscles increases
- D. Blood viscosity thickens
Correct Answer: C
Rationale: During exercise, the cardiovascular response includes an increase in blood flow to the muscles to deliver more oxygen and nutrients needed for energy production. This helps to support the increased demand for oxygen and nutrients by the working muscles. Blood pressure typically increases during exercise to help facilitate this increased blood flow to the muscles. Additionally, blood vessel diameter may widen (vasodilation) to allow for more blood flow, rather than narrow. Blood viscosity does not typically thicken during exercise.
The process by which a single-celled organism divides into two identical daughter cells is called
- A. Conjugation
- B. Binary fission
- C. Endocytosis
- D. Mitosis
Correct Answer: B
Rationale: Rationale:
A) Conjugation is a process in which genetic material is transferred between two bacterial cells through a conjugation tube. It does not involve the division of a single-celled organism into two identical daughter cells.
B) Binary fission is the process by which a single-celled organism, such as a bacterium, divides into two identical daughter cells. This is a common method of reproduction in prokaryotic organisms.
C) Endocytosis is a cellular process in which cells engulf external materials by wrapping them in a vesicle. It is not a method of cell division.
D) Mitosis is a type of cell division that occurs in eukaryotic cells, leading to the production of two daughter cells with identical genetic material. However, the question specifically refers to a single-celled organism, which typically undergoes binary fission for reproduction.