Nursing Elites

1. What is the molarity of a solution containing 45 moles of NaCl in 4 liters?

• A. 0.11 M NaCl
• B. 0.45 M NaCl
• C. 1.8 M NaCl
• D. 8.9 M NaCl

Correct answer: A

Rationale: To calculate the molarity of a solution, you use the formula: Molarity (M) = moles of solute / liters of solution. In this case, M = 45 moles / 4 L = 11.25 M. The correct answer is 0.11 M NaCl. Choice B is incorrect as it doesn't match the calculated value. Choice C is also incorrect as it is significantly higher than the correct molarity. Choice D is incorrect as it is excessively high compared to the calculated value.

2. Which one does not name a polar molecule?

• A. NH₃
• B. H₂S
• C. SO₂
• D. CO₂

Correct answer: A

Rationale: The correct answer is NH₃. The molecule NH₃ does not represent a polar molecule because nitrogen and hydrogen in this molecule have a small difference in electronegativity that does not result in a significant polar covalent bond. In contrast, molecules H₂S, SO₂, and CO₂ have polar covalent bonds due to larger electronegativity differences, making them polar molecules. Therefore, options B, C, and D are polar molecules, unlike option A.

3. How can the reaction rate of a chemical reaction be increased?

• A. Increase the temperature
• B. Increase the surface area
• C. Increase the concentration of reactants
• D. Add a catalyst

Correct answer: A

Rationale: To increase the reaction rate of a chemical reaction, one effective method is to increase the temperature. Raising the temperature provides more energy to the reacting particles, enabling them to collide more frequently and with higher energy, leading to an increase in the reaction rate. While increasing the surface area, concentration of reactants, and adding a catalyst are strategies that can also enhance the reaction rate, raising the temperature has the most direct and immediate impact. Increasing the surface area allows for more contact between reactants, increasing the concentration provides more reactant particles to collide, and adding a catalyst lowers the activation energy required for the reaction to occur. However, these methods may not have as immediate and significant an effect as increasing the temperature.

4. Which gas is released during photosynthesis?

• A. Carbon dioxide
• B. Oxygen
• C. Nitrogen
• D. Helium

Correct answer: B

Rationale: During photosynthesis, plants utilize carbon dioxide and water to produce glucose and oxygen. Oxygen is released as a byproduct of this process, which is essential for the survival of most living organisms that depend on it for respiration. Therefore, the correct answer is oxygen. Choices A, C, and D are incorrect. Carbon dioxide is utilized in photosynthesis, nitrogen is not directly involved in the process, and helium is not a gas released during photosynthesis.

5. Which particles are emitted during radioactivity?

• A. Electrons
• B. Protons
• C. Radiation
• D. Neutrons

Correct answer: C

Rationale: During radioactivity, radiation is emitted from an unstable nucleus. This radiation can take various forms like alpha particles, beta particles, or gamma rays. These particles or rays are emitted as a result of the unstable nucleus's attempt to achieve a more stable configuration. Therefore, the correct answer is radiation (Choice C). Electrons (Choice A), protons (Choice B), and neutrons (Choice D) are not typically emitted during radioactivity, as the emission is primarily in the form of radiation.

Similar Questions