Nursing Elites

1. Which of the following elements is a halogen?

• A. Oxygen
• B. Fluorine
• C. Sodium
• D. Carbon

Correct answer: B

Rationale: The correct answer is 'Fluorine' (Choice B) as it is a halogen. Halogens are a group of elements that include fluorine, chlorine, bromine, iodine, and astatine. They are highly reactive nonmetals located in Group 17 of the periodic table. Oxygen (Choice A) is a nonmetal but not a halogen. Sodium (Choice C) is a metal, and Carbon (Choice D) is a nonmetal, neither of which belong to the halogen group.

2. Which factor does not affect the reaction rate of a chemical reaction?

• A. Temperature
• B. Surface area
• C. Concentration of reactants
• D. Color of the reactants

Correct answer: D

Rationale: The color of reactants is not a factor that affects the rate of a chemical reaction. Temperature, surface area, and concentration of reactants are known factors that influence the reaction rate. Temperature plays a significant role in altering the reaction rate by affecting the kinetic energy of molecules. Surface area impacts the rate by providing more area for collisions to occur. Concentration affects the frequency of effective collisions. On the other hand, the color of reactants is a physical property that does not directly affect the speed of a chemical reaction.

3. A chemist takes 100 mL of a 40 g NaCl solution and dilutes it to 1L. What is the concentration (molarity) of the new solution?

• A. 0.04 M NaCl
• B. 0.25 M NaCl
• C. 0.40 M NaCl
• D. 2.5 M NaCl

Correct answer: C

Rationale: Initially, the chemist has 40 g of NaCl in 100 mL of solution. To find the initial molarity, we need to calculate the number of moles of NaCl using the molar mass of NaCl (58.44 g/mol). After dilution to 1 L, the molarity of the new solution can be calculated by dividing the moles of NaCl by the total volume in liters. Therefore, the concentration (molarity) of the new solution is 0.40 M NaCl. Choice A (0.04 M NaCl) is incorrect because it doesn't consider the correct molar concentration after dilution. Choice B (0.25 M NaCl) is incorrect as it also doesn't account for the correct molar concentration post-dilution. Choice D (2.5 M NaCl) is incorrect as it is too concentrated given the initial amount of NaCl and the dilution factor.

4. How many electron pairs are shared to form a triple covalent bond?

• A. 1
• B. 2
• C. 3
• D. 4

Correct answer: C

Rationale: The correct answer is C. In a triple covalent bond, three pairs of electrons are shared between two atoms. This sharing results in a total of six electrons being shared, making the bond strong. Choice A (1) is incorrect because a single covalent bond involves the sharing of one pair of electrons. Choice B (2) is incorrect as a double covalent bond consists of the sharing of two pairs of electrons. Choice D (4) is incorrect because there are only three pairs of electrons shared in a triple covalent bond, not four.

5. What creates a dipole in a covalent bond?

• A. Unequal sharing of electrons
• B. Equal sharing of electrons
• C. Exchange of electrons
• D. Transfer of electrons

Correct answer: A

Rationale: A dipole is created in a covalent bond when there is an unequal sharing of electrons between the atoms involved. This results in a partial positive charge on one atom and a partial negative charge on the other, leading to a separation of charges and the formation of a dipole. Choices B, C, and D are incorrect because a dipole is specifically formed due to unequal sharing of electrons, not equal sharing, exchange, or transfer of electrons in a covalent bond.

Similar Questions