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What is the term for the reactant that is fully consumed by the reaction?
- A. limiting reactant
- B. reducing agent
- C. reaction intermediate
- D. reagent
Correct Answer: A
Rationale: The correct answer is 'limiting reactant.' In a chemical reaction, the limiting reactant is the substance that is entirely consumed when the reaction proceeds. It determines the extent of the reaction and limits the amount of product that can be formed. The other choices, such as 'reducing agent,' 'reaction intermediate,' and 'reagent,' do not specifically refer to the reactant that is fully consumed in the reaction.
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Which type of bond involves atoms gaining or losing electrons?
- A. Ionic
- B. Covalent
- C. Both
- D. Neither
Correct Answer: A
Rationale: Ionic bonds involve the transfer of electrons between atoms, leading to one atom gaining electrons (becoming negatively charged) while the other loses electrons (becoming positively charged). This results in the formation of ions that are held together by electrostatic forces, creating an ionic bond. In a covalent bond, atoms share electrons rather than gaining or losing them, making option A, 'Ionic,' the correct answer to this question. Therefore, the correct answer is 'Ionic,' as it specifically involves gaining or losing electrons to form a bond.
What are van der Waals forces?
- A. the weak forces of attraction between two molecules
- B. the strong forces of attraction between two molecules
- C. hydrogen bonds
- D. conjugal bonds
Correct Answer: A
Rationale: Van der Waals forces are weak intermolecular forces that occur between non-polar molecules. These forces result from temporary fluctuations in electron distribution within the molecules, leading to slight positive and negative charges. This results in weak attraction between molecules through van der Waals forces. Hydrogen bonds, in contrast, are stronger intermolecular forces that specifically occur between molecules containing hydrogen bonded to a highly electronegative atom like oxygen or nitrogen. Conjugal bonds do not exist in chemistry and are not relevant to intermolecular forces.
What is the name for the horizontal rows of the periodic table?
- A. groups
- B. periods
- C. families
- D. sets
Correct Answer: B
Rationale: In the periodic table, the horizontal rows are called 'periods.' These periods represent the number of electron shells an element has. Each period starts a new energy level, indicating the elements' properties and atomic structure. 'Groups' refer to the vertical columns of the periodic table, each containing elements with similar chemical properties. 'Families' can also be used interchangeably with groups. 'Sets' is a vague term and not specifically related to the layout of the periodic table. Understanding the distinction between 'periods' and 'groups' is crucial in comprehending the organization and properties of elements in the periodic table.
What characterizes bases or alkaline solutions?
- A. Hydrogen acceptors
- B. Solutions of low pH
- C. Hydrogen donors
- D. Amphoteric
Correct Answer: A
Rationale: Bases or alkaline solutions are characterized by their ability to accept protons (hydrogen ions), making them hydrogen acceptors. When a base reacts with an acid, it accepts protons from the acid, forming water and a salt. This property distinguishes bases from acids, which donate protons. Therefore, the correct choice is A, as bases do not donate protons but instead accept them. This property allows bases to neutralize acids and regulate pH levels in solutions, making them crucial in maintaining the balance of acidity and alkalinity in various chemical systems.
What is a benefit of water's ability to make hydrogen bonds?
- A. Lack of cohesiveness
- B. Low surface tension
- C. Use as a nonpolar solvent
- D. High specific heat
Correct Answer: D
Rationale: The correct answer is D - High specific heat. Water's ability to make hydrogen bonds leads to a high specific heat capacity, which allows it to absorb and release large amounts of heat with minimal temperature change. This property is crucial for maintaining stable temperatures in living organisms and aquatic environments. High specific heat helps regulate body temperature in organisms and prevents sudden temperature fluctuations in water bodies, providing an essential benefit for various biological processes.