Nursing Elites

1. 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.

2. Which of the following is not an allotrope of carbon?

• A. Diamond
• B. Graphite
• C. Fluorine
• D. Buckminsterfullerene

Correct answer: C

Rationale: The correct answer is C: Fluorine. Allotropes of carbon are different forms of the same element. Diamonds, graphite, and buckminsterfullerene are all allotropes of carbon. However, fluorine is a separate chemical element and not an allotrope of carbon. Therefore, fluorine does not belong to the group of carbon allotropes.

3. Which of the following compounds is ionic?

• A. NaCl
• B. H₂O
• C. HCl
• D. NH₃

Correct answer: A

Rationale: The correct answer is NaCl (sodium chloride). Ionic compounds are formed by the transfer of electrons between a metal and a nonmetal. In NaCl, sodium (Na) is a metal, and chlorine (Cl) is a nonmetal. Sodium donates an electron to chlorine, leading to the formation of the ionic bond between them. This results in the formation of an ionic compound, where positively charged sodium ions are attracted to negatively charged chloride ions, creating a crystal lattice structure. Choices B, C, and D are not ionic compounds. H₂O (water) is a covalent compound formed by the sharing of electrons between two nonmetals (oxygen and hydrogen). HCl (hydrogen chloride) and NH₃ (ammonia) are also covalent compounds involving nonmetals sharing electrons, not transferring them.

4. Which ion would you expect to dominate in water solutions of bases?

• A. MgCl₂
• B. 2HCl
• C. H⁺
• D. OH⁻

Correct answer: D

Rationale: In water solutions of bases, the dominant ion would be OH⁻ (hydroxide ion). Bases release OH⁻ ions when dissolved in water, increasing the concentration of hydroxide ions and leading to a higher pH. This is in contrast to acids, which release H⁺ ions. Therefore, in water solutions of bases, the presence of OH⁻ ions signifies the basic nature of the solution. Choices A, B, and C are incorrect because MgCl₂ is a salt, 2HCl is a compound consisting of two hydrogen ions and one chloride ion, and H⁺ represents a hydrogen ion typically associated with acids, not bases.

5. You contain two odorous gases in vials with porous plugs. Gas A has twice the mass of Gas B. Which observation is most likely?

• A. You will smell Gas A before you smell Gas B.
• B. You will smell Gas B before you smell Gas A.
• C. You will smell Gas A but not Gas B.
• D. You will smell Gas B but not Gas A.

Correct answer: A

Rationale: The rate of effusion of a gas is inversely proportional to the square root of its molar mass. Since Gas A has twice the mass of Gas B, Gas A will effuse more slowly than Gas B. Therefore, you will likely smell Gas A before you smell Gas B as Gas A will escape and diffuse through the porous plug at a slower rate compared to Gas B. Choice A is correct because Gas A, with its higher molar mass, will take longer to effuse through the porous plug, causing you to smell it first. Choices B, C, and D are incorrect as they do not consider the relationship between molar mass and effusion rate.

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