Nursing Elites

1. Radioactive isotopes are frequently used in medicine. What kind of half-life would a medical isotope probably have?

• A. Seconds-long
• B. Days-long
• C. Years-long
• D. Many years long

Correct answer: B

Rationale: Medical isotopes used in diagnosis and treatment need to have a relatively short half-life to minimize radiation exposure to patients. If the half-life were too long (such as many years) or even years-long, the radiation would persist for too long and could be harmful to the patient. Seconds-long half-lives would not provide enough time for the isotope to be effective. Days-long half-lives strike a balance between providing enough time for the isotope to be used effectively and minimizing radiation exposure.

2. How many amino acids are essential for human life?

• A. 22
• B. 20
• C. 18
• D. 24

Correct answer: B

Rationale: There are 20 essential amino acids required for human life. These amino acids cannot be synthesized by the body and must be obtained through the diet. They play crucial roles in various physiological functions and are necessary for protein synthesis and overall health. Choice A is incorrect because there are not 22 essential amino acids. Choice C is incorrect as there are more than 18 essential amino acids. Choice D is incorrect as there are not 24 essential amino acids for human life.

3. What is the simplest form of a substance that is represented by a letter or letters?

• A. Compound
• B. Mixture
• C. Element
• D. Molecule

Correct answer: C

Rationale: The correct answer is C, 'Element.' An element is the most basic form of a substance that cannot be broken down further by chemical reactions. Each element is represented by a unique symbol, typically consisting of one or two letters. Choice A, 'Compound,' is incorrect as compounds are formed by the combination of two or more elements. Choice B, 'Mixture,' is also incorrect as mixtures are composed of two or more substances physically combined. Choice D, 'Molecule,' refers to the smallest unit of a compound that retains the chemical properties of that compound, not the simplest form of a substance represented by a symbol.

4. How much concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution?

• A. 75 mL
• B. 100 mL
• C. 125 mL
• D. 150 mL

Correct answer: B

Rationale: To prepare a 0.100 M HCl solution with a volume of 500 mL, you can use the formula C1V1 = C2V2, where C1 is the concentration of the concentrated HCl solution, V1 is the volume of concentrated HCl solution used, C2 is the desired concentration (0.100 M), and V2 is the final volume (500 mL). Rearranging the formula to solve for V1, you get V1 = (C2V2) / C1. Plugging in the values (0.100 M)(500 mL) / C1 = 100 mL, which means 100 mL of concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution. Therefore, the correct answer is 100 mL. Choice A (75 mL), Choice C (125 mL), and Choice D (150 mL) are incorrect as they do not match the calculated volume needed to prepare the desired concentration of HCl solution.

5. What type of reaction involves atoms attempting to achieve stable electron configurations?

• A. Chemical
• B. Nuclear
• C. Physical
• D. Mechanical

Correct answer: A

Rationale: In a chemical reaction, atoms interact to achieve stable electron configurations through the formation of new chemical bonds or the breaking of existing ones. This process aims to reach a more stable state by filling or emptying electron orbitals, leading to the formation of new substances with more stable configurations. Choice B, nuclear reactions, involve changes in the atomic nucleus rather than electron configurations. Choice C, physical reactions, involve changes in physical state or appearance without changing the chemical makeup. Choice D, mechanical reactions, do not involve the rearrangement of electrons to achieve stable configurations.

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