Nokea
What is the term for the process of a liquid changing into a gas?
- A. Evaporation
- B. Boiling
- C. Condensation
- D. Sublimation
Correct Answer: A
Rationale: The correct answer is 'Evaporation.' Evaporation is the process by which a liquid changes into a gas at any temperature, while boiling specifically refers to the rapid vaporization of a liquid only at its boiling point. Condensation is the opposite process of gas turning into a liquid, and sublimation is the direct transition from solid to gas without passing through the liquid phase.
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What is the term for a group of organisms that can interbreed and produce fertile offspring?
- A. Genus
- B. Phylum
- C. Kingdom
- D. Species
Correct Answer: D
Rationale: A species is defined as a group of organisms that can interbreed and produce fertile offspring, which is a fundamental concept in biology. This ability to interbreed and produce fertile offspring is a key characteristic that distinguishes one species from another. Genus (option A) refers to a taxonomic rank that includes one or more closely related species, not the ability to interbreed. Phylum (option B) and kingdom (option C) are higher taxonomic ranks that encompass a broader range of organisms, not specifically defined by interbreeding and fertile offspring production. Therefore, the correct answer is 'Species.'
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 NOT a mechanism of evolution?
- A. Natural selection
- B. Genetic drift
- C. Lamarckism
- D. Mutation
Correct Answer: C
Rationale: A) Natural selection is a mechanism of evolution where individuals with advantageous traits are more likely to survive and reproduce, passing on those traits to the next generation.
B) Genetic drift is a mechanism of evolution that occurs due to random changes in allele frequencies in a population.
C) Lamarckism, also known as the inheritance of acquired characteristics, is a discredited theory that suggests organisms can pass on traits acquired during their lifetime to their offspring. This mechanism has been largely rejected by the scientific community.
D) Mutation is a mechanism of evolution that introduces new genetic variation into a population, which can lead to the emergence of new traits and adaptations over time.
Vacuoles are large sacs for storage in plant cells. What is their main function in animal cells?
- A. Protein synthesis
- B. Waste storage and disposal
- C. Photosynthesis
- D. Cellular respiration
Correct Answer: B
Rationale: Vacuoles in animal cells primarily function in waste storage and disposal, helping to maintain cellular homeostasis by storing waste products and aiding in their removal from the cell. Unlike plant cells, animal cells do not typically use vacuoles for storage purposes such as water, nutrients, or pigments. Instead, animal cells rely on other organelles like lysosomes for waste management and maintaining cellular balance. Choices A, C, and D are incorrect because protein synthesis occurs in ribosomes, photosynthesis takes place in chloroplasts (absent in animal cells), and cellular respiration mainly occurs in mitochondria, respectively. Vacuoles in animal cells serve a different purpose compared to plant cells.
When two objects with different masses collide, what happens to their momentum after the collision?
- A. Increases for both objects
- B. Decreases for both objects
- C. Remains the same for both objects
- D. Can increase for one and decrease for the other
Correct Answer: C
Rationale: When two objects with different masses collide, their total momentum remains the same after the collision according to the law of conservation of momentum if no external forces are acting on them. This means that the momentum of each individual object may change, but the sum of their momenta will remain constant. Choice A is incorrect because the total momentum of the system is conserved. Choice B is incorrect because momentum is conserved in an isolated system. Choice D is incorrect as it implies a violation of the law of conservation of momentum, which states that the total momentum of an isolated system remains constant.