Nokea
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.
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What is the difference between a real image and a virtual image formed by a lens?
- A. Real images can be projected onto a screen, while virtual images cannot.
- B. Real images are always upright, while virtual images can be inverted.
- C. Real images are formed by converging lenses, while virtual images are formed by diverging lenses.
- D. All of the above are true.
Correct Answer: A
Rationale: The correct answer is A. Real images can be projected onto a screen because they are formed by the actual convergence of light rays, while virtual images cannot be projected onto a screen as they appear to diverge from a point behind the lens. Real and virtual images do not have a consistent orientation (upright or inverted), so option B is incorrect. Real images are formed by both converging and diverging lenses depending on the specific scenario, so option C is not a definitive distinction. Option D is incorrect as not all the statements are true. Therefore, the only accurate general distinction between real and virtual images is that real images can be projected onto a screen, while virtual images cannot.
Which structure in the respiratory system is responsible for preventing food and liquids from entering the trachea during swallowing?
- A. Bronchi
- B. Larynx
- C. Alveoli
- D. Pharynx
Correct Answer: B
Rationale: The larynx, housing the epiglottis, a flap of tissue, is the structure responsible for preventing food and liquids from entering the trachea during swallowing. It acts as a protective barrier, covering the trachea to ensure that ingested substances are directed to the esophagus. The bronchi are the primary airway passages that branch from the trachea into the lungs. Alveoli are tiny air sacs in the lungs where gas exchange occurs, facilitating the exchange of oxygen and carbon dioxide. The pharynx is the passage connecting the mouth and nasal cavity to the esophagus and trachea.
What is the primary function of the strong nuclear force?
- A. Binding electrons in atomic orbitals
- B. Binding protons and neutrons within the nucleus
- C. Mediating the attractive force between opposite charges
- D. Mediating the repulsive force between like charges
Correct Answer: B
Rationale: The strong nuclear force primarily functions to bind protons and neutrons within the nucleus. It is responsible for overcoming the electrostatic repulsion between positively charged protons, holding the nucleus together. Choices A, C, and D are incorrect because the strong nuclear force specifically acts on nucleons (protons and neutrons) within the nucleus, not on electrons in atomic orbitals or charges outside the nucleus.
Chyle, a milky white fluid, is transported by lymphatic vessels from the:
- A. Lungs
- B. Intestines
- C. Kidneys
- D. Skin
Correct Answer: B
Rationale: Chyle, a milky white fluid, is formed in the small intestine during digestion. It is composed of lymph and emulsified fats. Lymphatic vessels in the intestines, specifically lacteals, transport chyle from the intestines to the bloodstream for the distribution of nutrients throughout the body. The transport of chyle from the lungs, kidneys, or skin is not correct as these organs are not primarily involved in the production or transportation of chyle.
Which of the following describes a scalar quantity?
- A. Velocity
- B. Acceleration
- C. Force
- D. Speed
Correct Answer: D
Rationale: A scalar quantity is a physical quantity that has magnitude only, without any direction. Speed is an example of a scalar quantity because it only describes how fast an object is moving without specifying the direction of motion. Velocity, acceleration, and force are vector quantities because they have both magnitude and direction. Therefore, the correct answer is 'Speed.' Choices A, B, and C are incorrect because velocity, acceleration, and force are all vector quantities that involve both magnitude and direction.