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. What is the boiling point of water in °C?

• A. 90°C
• B. 100°C
• C. 95°C
• D. 80°C

Correct answer: B

Rationale: The correct answer is 100°C. The boiling point of water in Celsius is 100°C, which is standard at sea level. This is the temperature at which water changes from a liquid to a gas phase under standard atmospheric pressure. Choice A (90°C), Choice C (95°C), and Choice D (80°C) are incorrect because they do not represent the standard boiling point of water at sea level.

3. Which of the following compounds is ionic?

• A. NaCl
• B. Hâ‚‚O
• 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. How many neutrons does carbon-14 have?

• A. 10
• B. 8
• C. 6
• D. 12

Correct answer: B

Rationale: The correct answer is B: 8. Carbon-14 is an isotope of carbon with 6 protons and 8 neutrons. To determine the number of neutrons in an atom, subtract the atomic number (number of protons) from the mass number. In this case, the mass number of carbon-14 is 14, and the atomic number of carbon is 6. Therefore, 14 (mass number) - 6 (atomic number) = 8 neutrons. Choices A, C, and D are incorrect because they do not reflect the correct number of neutrons in a carbon-14 atom.

5. Which two elements are most alike in reactivity?

• A. He and H
• B. K and Ar
• C. Cl and P
• D. Ba and Mg

Correct answer: C

Rationale: Chlorine (Cl) and Phosphorus (P) are most alike in reactivity among the given pairs. Both elements are nonmetals and belong to Group 7 (halogens) and Group 15 (nitrogen group), respectively. They have similar electronic configurations and can form compounds by gaining or sharing electrons. Chlorine is highly reactive and can easily form ionic compounds, while phosphorus also shows a range of reactivity in its compounds. Choice A (He and H) is incorrect because helium (He) is a noble gas and hydrogen (H) is a nonmetal, so they are not similar in reactivity. Choice B (K and Ar) is incorrect as potassium (K) is a metal and argon (Ar) is a noble gas, having different reactivities. Choice D (Ba and Mg) is incorrect because barium (Ba) and magnesium (Mg) are both metals, but their reactivities differ due to their positions in the periodic table.

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