Nursing Elites

1. Which type of change occurs when no change is made to the chemical composition of a substance?

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

Correct answer: B

Rationale: A physical change refers to alterations in the state of matter without modifying the chemical composition of the substance. Examples of physical changes include changes in state (solid, liquid, gas), shape, size, or phase. In a physical change, the substance may look different or behave differently, but its chemical structure remains the same. On the other hand, chemical changes involve the breaking and forming of chemical bonds, resulting in the creation of entirely new substances with different chemical properties. Nuclear changes involve alterations in the nucleus of an atom, such as radioactive decay. Mechanical changes refer to changes in the position or motion of an object caused by applied forces, like pushing, pulling, or twisting.

2. 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.

3. What is the correct electron configuration for magnesium?

• A. 1s² 2s²
• B. 1s² 2s² 2p⁶
• C. 1s² 2s² 2p⁶ 3s²
• D. 1s² 2s² 2p⁶ 3s² 3p¹

Correct answer: C

Rationale: The electron configuration of an element is determined by following the Aufbau principle, which states that electrons fill orbitals starting from the lowest energy level. Magnesium has an atomic number of 12, meaning it has 12 electrons. The electron configuration of magnesium fills the 1s, 2s, 2p, and 3s orbitals to accommodate all 12 electrons. Therefore, the correct electron configuration for magnesium is 1s² 2s² 2p⁶ 3s². Choice A is incorrect as it only includes 4 electrons and stops at the 2s orbital. Choice B is incorrect as it includes 8 electrons and stops at the 2p orbital. Choice D is incorrect as it includes 13 electrons and extends to the 3p orbital, which is beyond the actual electron configuration of magnesium.

4. What type of radiation is high-energy electromagnetic radiation that lacks charge and mass?

• A. Beta
• B. Alpha
• C. Gamma
• D. Delta

Correct answer: C

Rationale: Gamma radiation is a form of high-energy electromagnetic radiation that does not possess charge or mass. This type of radiation is commonly used in various fields due to its penetrating ability and lack of charge or mass, making it different from alpha and beta radiation, which consist of charged particles. Therefore, the correct answer is C - Gamma. Choices A and B are incorrect as they refer to alpha and beta radiation, which are composed of charged particles. Choice D, Delta, is not a type of radiation.

5. What is the oxidation state of the sulfur atom in sulfuric acid H2SO4?

• A. 4
• B. 6
• C. 8
• D. 10

Correct answer: B

Rationale: In sulfuric acid (H2SO4), sulfur has an oxidation state of +6. The oxidation state is determined by considering the overall charge of the compound and the known oxidation states of other elements. In this case, hydrogen is typically +1, and oxygen is -2. To balance the charges and match the compound's overall charge of 0, sulfur must have an oxidation state of +6. Choice A (4) is incorrect because it doesn't balance the charges in the compound. Choices C (8) and D (10) are also incorrect as they are not valid oxidation states for sulfur in this compound.

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