Chemistry HESI A2 Quizlet

Correct Answer: C

Rationale: Increasing the surface area of a reactant increases the number of exposed particles available for collision, leading to more frequent and successful collisions. This results in an increased reaction rate. Choice A is incorrect because more surface area facilitates faster reactions. Choice B is incorrect as surface area affects reaction rate. Choice D is incorrect as increasing surface area does not stop the reaction; it actually accelerates it.

Correct Answer: B

Rationale: The correct answer is B: Double replacement. In this type of reaction, two ionic compounds swap ions to form two new compounds. The cations and anions switch partners, leading to the formation of two different ionic compounds. This process is also known as metathesis. Single replacement (A) involves an element replacing another in a compound. Synthesis (C) involves the combination of two or more substances to form a single compound. Decomposition (D) involves a single compound breaking down into simpler substances. Double replacement is the only option where two ionic compounds exchange partners, making it the correct choice in this scenario.

Correct Answer: C

Rationale: The correct answer is C: Several feet of concrete. Gamma radiation is highly penetrating and requires dense materials to effectively block it. Concrete, being a dense material, can absorb and block gamma radiation effectively due to its high atomic number and thickness. Aluminum foil (A) and glass (B) are not dense enough to stop gamma radiation. Paper (D) is too thin and lacks the density needed to block gamma radiation effectively.

Correct Answer: C

Rationale: The correct answer is C: Electronegativity. Polarity in a molecule is determined by the difference in electronegativity between atoms forming a bond. The greater the electronegativity difference, the more polar the bond and molecule. This is because electronegativity measures an atom's ability to attract electrons towards itself. Bond length (A) and bond strength (B) do not directly determine polarity, although shorter and stronger bonds can influence polarity indirectly. Molecular weight (D) is not a factor in determining polarity, as it relates to the total mass of a molecule rather than its polarity.

Correct Answer: D

Rationale: The correct answer is D: Color of the reactants. The color of the reactants does not affect the reaction rate as it is a purely visual characteristic and does not influence the speed at which the reaction occurs. Temperature affects reaction rate by providing energy for molecules to react faster. Surface area influences reaction rate by increasing the area of contact between reactants. Concentration of reactants affects reaction rate by increasing the frequency of collisions between molecules. In summary, factors like temperature, surface area, and concentration directly impact reaction rate, whereas color is merely a visual property and does not play a role in determining the speed of a chemical reaction.