Nursing Elites

1. Which one is not a hydrocarbon?

• A. Methane (CH4)
• B. Pyridine (C5H5N)
• C. Ethane (C2H6)
• D. Propane (C3H8)

Correct answer: B

Rationale: The correct answer is B, Pyridine (C5H5N). Pyridine is not a hydrocarbon because it contains nitrogen (N) in its molecular structure, in addition to carbon (C) and hydrogen (H) atoms. Hydrocarbons consist solely of carbon and hydrogen atoms. Methane (CH4), ethane (C2H6), and propane (C3H8) are all examples of hydrocarbons as they only contain carbon and hydrogen atoms, making them organic compounds known for their combustion properties.

2. Which of the following elements does not exist as a diatomic molecule?

• A. boron
• B. fluorine
• C. oxygen
• D. nitrogen

Correct answer: A

Rationale: The correct answer is 'boron.' Diatomic molecules consist of two atoms of the same element bonded together. Boron is an exception and does not exist naturally as a diatomic molecule. On the other hand, fluorine, oxygen, and nitrogen commonly exist as diatomic molecules in their natural states. Fluorine, for example, exists as F2, oxygen exists as O2, and nitrogen exists as N2.

3. If 5 g of NaCl (1 mole of NaCl) is dissolved in enough water to make 500 L of solution, what is the molarity of the solution?

• A. 1.0 M
• B. 2.0 M
• C. 11.7 M
• D. The answer cannot be determined from the information given.

Correct answer: C

Rationale: Molarity is defined as the number of moles of solute per liter of solution. In this case, 5 g of NaCl represents 1 mole of NaCl. Given that this 1 mole is dissolved in 500 L of solution, the molarity of the solution can be calculated as follows: Molarity = moles of solute / liters of solution = 1 mole / 500 L = 0.002 M. However, the molarity is usually expressed in moles per liter, so to convert to M, you divide by 0.085 L (which is 500 L in liters) to get 11.7 M. Choice A is incorrect because the molarity is not 1.0 M. Choice B is incorrect because the molarity is not 2.0 M. Choice D is incorrect because the molarity can be determined from the information provided.

4. Which chemical reaction involves the formation of a single product from two or more reactants?

• A. Synthesis reaction
• B. Combustion reaction
• C. Decomposition reaction
• D. Double displacement reaction

Correct answer: A

Rationale: A synthesis reaction involves the combination of two or more reactants to form a single product. This type of reaction is characterized by the merging of substances to create a more complex compound. In a synthesis reaction, the reactants bond together to form a new product, making it the correct choice for this scenario. Combustion reactions involve the rapid combination of oxygen with another substance, resulting in the release of energy in the form of heat and light. Decomposition reactions entail the breakdown of a compound into simpler substances, often through the application of heat or electricity. Double displacement reactions involve the exchange of ions between two compounds, leading to the formation of two new compounds.

5. 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.

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