Nokea
What is the coefficient of oxygen in the balanced chemical equation for the combustion of methane (CHâ‚„)?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: B
Rationale: In the balanced chemical equation for the combustion of methane, CH₄ + 2O₂ → CO₂ + 2H₂O, the coefficient of oxygen (O₂) is 2. This indicates that two molecules of oxygen are required to react with one molecule of methane to produce carbon dioxide and water, ensuring the equation is balanced. Choice A is incorrect because the coefficient of oxygen is not 1 but 2. Choices C and D are incorrect as they do not represent the correct coefficient of oxygen in the balanced equation. Understanding the coefficients in a balanced chemical equation is crucial for accurately representing the stoichiometry of the reaction.
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The van't Hoff factor (i) accounts for the number of particles a solute dissociates into in solution. For a compound that dissociates completely in water, i would be...
- B. Less than 1
- C. 1
- D. More than 1
Correct Answer: D
Rationale: The van't Hoff factor (i) represents the number of particles a solute dissociates into in solution. For a compound that dissociates completely in water, i would be more than 1 because it breaks apart into more particles than the original compound. This is due to complete dissociation leading to an increase in the number of particles in solution, resulting in i being greater than 1. Choice A is incorrect as a compound that dissociates completely will not have an i value of 0. Choice B is incorrect because when a compound dissociates completely, the van't Hoff factor is not less than 1. Choice C is incorrect as a compound that dissociates completely will not have an i value of 1, but rather more than 1 due to the increased number of particles in solution.
During which stage of meiosis II are sister chromatids separated, resulting in four genetically unique daughter cells?
- A. Prophase I
- B. Prophase II
- C. Anaphase I
- D. Anaphase II
Correct Answer: D
Rationale: - Prophase I occurs in meiosis I, not meiosis II. During Prophase I, homologous chromosomes pair up and exchange genetic material in a process called crossing over.
- Prophase II is the stage where the nuclear envelope breaks down, and spindle fibers start to reappear, preparing the cell for division. Sister chromatids are still attached during Prophase II.
- Anaphase I is the stage in meiosis I where homologous chromosomes are separated and pulled to opposite poles of the cell.
- Anaphase II is the stage in meiosis II where sister chromatids are separated and pulled to opposite poles of the cell, resulting in four genetically unique daughter cells. This is the stage where the final separation of genetic material occurs, leading to the formation of haploid daughter cells.
What is the process by which one element changes into another through radioactive decay known as?
- A. Transmutation
- B. Fission
- C. Fusion
- D. Oxidation
Correct Answer: A
Rationale: The correct answer is A: Transmutation. Transmutation is the correct term to describe the process by which one element changes into another element through radioactive decay. In transmutation, the atomic structure of the element is altered, leading to a change in the element's identity. Choice B, Fission, refers to the splitting of a heavy nucleus into lighter nuclei. Choice C, Fusion, involves the merging of lighter nuclei to form a heavier nucleus. Choice D, Oxidation, is not related to the process of one element changing into another through radioactive decay.
What is the difference between alpha decay and beta decay?
- A. Both release the same type of particle.
- B. Alpha decay releases a helium nucleus, while beta decay releases an electron or positron.
- C. Alpha decay is more common than beta decay.
- D. They both convert one element into another, but in different ways.
Correct Answer: B
Rationale: The correct answer is B. Alpha decay involves the release of a helium nucleus, which consists of two protons and two neutrons. In contrast, beta decay releases an electron (beta-minus decay) or a positron (beta-plus decay). This significant distinction in the particles emitted during the decay processes distinguishes alpha decay from beta decay. Choice A is incorrect because alpha and beta decay release different types of particles. Choice C is incorrect as beta decay is more common than alpha decay in many cases. Choice D is incorrect as it does not specifically address the particles released during alpha and beta decay.
Which bones are included in the axial skeleton?
- A. Head, neck, and trunk
- B. Arms and legs
- C. Hands and feet
- D. All of the above
Correct Answer: A
Rationale: The correct answer is A: Head, neck, and trunk. The axial skeleton comprises bones located in the head, neck, and trunk region, such as the skull, vertebral column, and rib cage. These bones provide structural support and protect vital organs like the brain, spinal cord, and heart. Choices B and C are incorrect because arms, legs, hands, and feet are part of the appendicular skeleton, not the axial skeleton. The appendicular skeleton is responsible for movement, manipulation, and mobility, while the axial skeleton primarily provides central support and protection for essential organs.