Nokea
What term describes the bending of waves around obstacles or through openings?
- A. Reflection
- B. Refraction
- C. Diffraction
- D. Absorption
Correct Answer: C
Rationale: The correct answer is C, Diffraction. Diffraction is the phenomenon that explains the bending of waves around obstacles or through openings. When waves encounter obstacles or pass through openings, they spread out and bend around them. Reflection (Choice A) involves waves bouncing back when they encounter a surface without bending, refraction (Choice B) is the bending of waves when passing from one medium to another due to a change in speed, and absorption (Choice D) is the process of a wave being taken in by a material rather than bending or bouncing.
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What is the difference between isometric and isotonic muscle contractions?
- A. Isometric involves movement, while isotonic does not.
- B. Isotonic involves shortening of muscle, while isometric maintains length.
- C. Isometric uses more energy, while isotonic uses less.
- D. Isotonic involves smooth muscle, while isometric involves skeletal muscle.
Correct Answer: B
Rationale: The correct answer is B. Isometric contractions occur when the muscle generates tension without changing its length, while isotonic contractions involve the muscle changing length to move a load. In isotonic contractions, the muscle shortens to move a load, whereas in isometric contractions, the muscle contracts to hold a position without movement. Choice A is incorrect because isometric contractions do not involve movement, while choice C is incorrect as isotonic contractions typically require more energy due to movement. Choice D is incorrect because the type of muscle involved (smooth or skeletal) is not the defining factor between isometric and isotonic contractions.
If you compare a 1 M solution of NaCl to a 1 M solution of glucose (C6H12O6) in water, which solution would have the higher boiling point?
- A. The NaCl solution
- B. The glucose solution
- C. They would have the same boiling point
- D. It depends on the temperature
Correct Answer: A
Rationale: 1. Boiling point elevation: When a solute is added to a solvent, it raises the boiling point of the solution compared to the pure solvent. This phenomenon is known as boiling point elevation.
2. Van't Hoff factor: The extent of boiling point elevation depends on the number of particles the solute dissociates into in the solution. NaCl dissociates into two ions (Na+ and Cl-) in water, while glucose does not dissociate into ions. Therefore, NaCl has a higher Van't Hoff factor than glucose.
3. Colligative properties: Boiling point elevation is a colligative property, meaning it depends on the concentration of the solute particles, not the identity of the solute. Since both NaCl and glucose are 1 M solutions, the NaCl solution will have a higher boiling point due to its higher Van't Hoff factor.
4. Conclusion: The NaCl solution
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 balanced chemical equation for the reaction between sulfuric acid (H2SO4) and potassium hydroxide (KOH)?
- A. H2SO4 + KOH → K2SO4 + H2O
- B. 2H2SO4 + 2KOH → 2K2SO4 + 2H2O
- C. H2SO4 + 2KOH → K2SO4 + 2H2O
- D. H2SO4 + 2KOH → K2SO4 + H2O
Correct Answer: C
Rationale: When sulfuric acid (H2SO4) reacts with potassium hydroxide (KOH), it forms potassium sulfate (K2SO4) and water (H2O). To balance the equation, 2 KOH molecules are required to react with 1 H2SO4 molecule, resulting in 1 K2SO4 molecule and 2 H2O molecules. Therefore, the balanced chemical equation is H2SO4 + 2KOH → K2SO4 + 2H2O, which corresponds to option C. Choice A is incorrect because it does not account for the correct stoichiometry between the reactants and products. Choice B incorrectly doubles all the molecules in the reaction, leading to an unbalanced equation. Choice D incorrectly balances the equation with 1 KOH molecule instead of the required 2 KOH molecules, making it unbalanced. Thus, option C is the correct balanced chemical equation for the reaction between sulfuric acid and potassium hydroxide.
Which of the following is a pair of nerves that originates from the brain?
- A. Spinal nerves
- B. Olfactory nerves
- C. Sciatic nerve
- D. Optic nerve
Correct Answer: B
Rationale: The olfactory nerves, choice B, are a pair of cranial nerves that originate from the brain. They are responsible for the sense of smell and are the only cranial nerves that directly connect to the cerebrum. Spinal nerves, choice A, originate from the spinal cord, the sciatic nerve, choice C, is a large nerve that originates in the lower back, and the optic nerve, choice D, originates from the retina of the eye. Therefore, choices A, C, and D are incorrect as they do not originate directly from the brain.