Nursing Elites

1. Which classification best describes B, Si, As, Te, At, Ge, and Sb that form a staircase pattern on the right side of the periodic table?

• A. Metals
• B. Semimetals
• C. Nonmetals
• D. Ultrametals

Correct answer: B

Rationale: B, Si, As, Te, At, Ge, and Sb are located in a staircase pattern on the periodic table's right side. Elements in this region are known as metalloids or semimetals because they exhibit properties of both metals and nonmetals. They possess characteristics of both metallic and non-metallic elements, making them valuable semiconductors with diverse applications in electronics. Choice A is incorrect because these elements are not considered true metals. Choice C is incorrect as these elements do not display typical nonmetal properties exclusively. Choice D, 'Ultrametals,' is not a recognized classification in chemistry and is therefore incorrect.

2. What effect does increasing the surface area of a reactant have?

• A. Decreases the reaction rate
• B. Has no effect
• C. Increases the reaction rate
• D. Stops the reaction

Correct answer: C

Rationale: Increasing the surface area of a reactant leads to more particles being exposed to the reaction, which in turn increases the reaction rate. This is because a larger surface area provides more sites for collisions between reacting particles, resulting in a higher frequency of successful collisions and thus accelerating the reaction. Choice A, 'Decreases the reaction rate,' is incorrect because increasing surface area actually accelerates the reaction. Choice B, 'Has no effect,' is incorrect as increasing surface area does have a significant effect on the reaction rate. Choice D, 'Stops the reaction,' is incorrect as increasing surface area does not stop the reaction but rather enhances it.

3. Which of the following compounds is ionic?

• A. NaCl
• B. H₂O
• 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. When an acid is added to a base, water and a salt form. What kinds of bonds form in these two compounds?

• A. Liquid and metallic
• B. Polar and nonpolar covalent
• C. Polar covalent and ionic
• D. Ionic only

Correct answer: C

Rationale: In water, the bond formed between the oxygen atom and the hydrogen atoms is a polar covalent bond. The oxygen atom attracts the shared electrons more strongly, creating a partial negative charge on the oxygen and a partial positive charge on the hydrogen atoms. In the salt formed, the bond between the metal cation and the nonmetal anion is predominantly an ionic bond. The metal cation donates electrons to the nonmetal anion, resulting in the formation of oppositely charged ions that are held together by electrostatic attractions. Choices A and B are incorrect because water and salts do not form bonds that are liquid and metallic, or polar and nonpolar covalent. Choice D is incorrect as it oversimplifies the types of bonds present in water and salts, failing to differentiate between the covalent bond in water and the ionic bond in the salt.

5. Which of the following is a characteristic of an exothermic reaction?

• A. It absorbs heat
• B. It releases heat
• C. It remains neutral
• D. It requires energy input

Correct answer: B

Rationale: An exothermic reaction is characterized by the release of heat. During an exothermic reaction, energy is released in the form of heat to the surroundings, resulting in a temperature increase. This distinguishes it from endothermic reactions, which absorb heat from the surroundings. Choice A is incorrect because exothermic reactions do not absorb heat; instead, they release heat. Choice C is incorrect as exothermic reactions do not remain neutral; they involve a net release of energy. Choice D is incorrect as exothermic reactions do not require energy input; instead, they release energy.

Similar Questions