Nursing Elites

1. What are the two types of chemical bonding?

• A. Covalent & hydrogen
• B. Ionic & covalent
• C. Ionic & hydrogen
• D. Covalent & metallic

Correct answer: B

Rationale: The correct answer is B: Ionic & covalent. Ionic bonding involves the transfer of electrons between atoms, resulting in the formation of positive and negative ions attracted to each other. Covalent bonding involves the sharing of electrons between atoms to achieve a stable electron configuration. Choice A is incorrect as hydrogen bonding is a type of intermolecular force, not a primary type of chemical bonding. Choice C is incorrect as hydrogen bonding is not a primary type of chemical bonding. Choice D is incorrect as metallic bonding involves the sharing of electrons in a 'sea of electrons' within a metal lattice, not covalent bonding.

2. Which of these represents a strong acid?

• A. CH₃COOH
• B. H₂SO₄
• C. NH₃
• D. KOH

Correct answer: B

Rationale: Among the options provided, H₂SO₄ (sulfuric acid) represents a strong acid. Strong acids completely ionize in water to produce a high concentration of H+ ions. Sulfuric acid is a strong acid known for its ability to dissociate almost completely in water, making it a strong acid. Choice A, CH₃COOH (acetic acid), is a weak acid that only partially dissociates in water. Choices C and D, NH₃ (ammonia) and KOH (potassium hydroxide), are bases and not acids.

3. A radioactive isotope has a half-life of 20 years. How many grams of a 6-gram sample will remain after 40 years?

• A. 8
• B. 6
• C. 3
• D. 1.5

Correct answer: C

Rationale: The half-life of a radioactive isotope is the time it takes for half of the original sample to decay. After each half-life period, half of the initial sample remains. In this case, after the first 20 years, half of the 6-gram sample (3 grams) will remain. After another 20 years (total of 40 years), half of the remaining 3 grams will remain, which is 1.5 grams. Therefore, 3 grams will be left after 40 years. Choice A is incorrect as it doesn't consider the concept of half-life and incorrectly suggests an increase in the sample. Choice B is incorrect as it assumes no decay over time. Choice D is incorrect as it miscalculates the remaining amount after two half-life periods.

4. On what concept is Kelvin based?

• A. Freezing point
• B. Absolute zero
• C. Boiling point
• D. Evaporation point

Correct answer: B

Rationale: The correct answer is B: Absolute zero. Kelvin is based on the concept of absolute zero, which is the point where molecular movement ceases entirely. This temperature scale starts at absolute zero (0K), where theoretically no molecular movement occurs. Choices A, C, and D are incorrect because Kelvin is not based on the freezing point, boiling point, or evaporation point, but rather on the absolute absence of molecular motion.

5. Which law states that matter can neither be created nor destroyed during a chemical reaction?

• A. Law of Conservation of Energy
• B. Law of Conservation of Mass
• C. Law of Constant Composition
• D. Law of Multiple Proportions

Correct answer: B

Rationale: The correct answer is B, the Law of Conservation of Mass. This law, formulated by Antoine Lavoisier, states that matter cannot be created or destroyed in a chemical reaction. It is a fundamental principle in chemistry that explains the preservation of mass during chemical reactions, indicating that the total mass of the reactants is equal to the total mass of the products. The other choices are incorrect because: A: The Law of Conservation of Energy states that energy cannot be created or destroyed, not matter. C: The Law of Constant Composition refers to compounds having the same composition by mass regardless of their source or how they were prepared, not about the conservation of matter in reactions. D: The Law of Multiple Proportions describes the ratios in which elements combine to form compounds, not the conservation of mass.

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