HESI A2 Chemistry - Nurselytic

Correct Answer: C

Rationale: Chlorine (Cl) and Phosphorus (P) are most alike in reactivity among the given pairs. Both elements are nonmetals and belong to Group 7 (halogens) and Group 15 (nitrogen group), respectively. They have similar electronic configurations and can form compounds by gaining or sharing electrons. Chlorine is highly reactive and can easily form ionic compounds, while phosphorus also shows a range of reactivity in its compounds.
Choice A (He and H) is incorrect because helium (He) is a noble gas and hydrogen (H) is a nonmetal, so they are not similar in reactivity.
Choice B (K and Ar) is incorrect as potassium (K) is a metal and argon (Ar) is a noble gas, having different reactivities.
Choice D (Ba and Mg) is incorrect because barium (Ba) and magnesium (Mg) are both metals, but their reactivities differ due to their positions in the periodic table.

Correct Answer: C

Rationale:
To balance the chemical equation Fe + O₂ → FeO, the coefficients needed are 2 for Fe and 1 for O.
Therefore, the balanced equation becomes 2Fe + O₂ → 2FeO, which translates into 2Fe + 3O₂ → 2FeO. This corresponds to option C.
Choice A has the incorrect number of oxygen molecules.
Choice B has an incorrect number of Fe atoms on the product side.
Choice D also has an incorrect number of Fe atoms on the product side.

Correct Answer: C

Rationale: A pentose is a 5-carbon sugar, as the prefix 'pent-' signifies five.
Therefore, a pentose sugar consists of five carbon atoms.
Choice A, 'A 6 carbon sugar,' is incorrect as a pentose sugar specifically has five carbons.
Choice B, 'A 4 carbon sugar,' is incorrect as it describes a tetrose sugar, which has four carbons.
Choice D, 'A 7 carbon sugar,' is incorrect as it does not correspond to the definition of a pentose sugar.

Correct Answer: B

Rationale: 0 Kelvin, also known as absolute zero, is equal to -273°C. This is the point at which all molecular motion stops, making it the lowest possible temperature on the Kelvin scale.
Choice A (-300°
C) is incorrect as it is not the correct conversion of 0 K to °C.
Choice C (-250°
C) and
Choice D (-200°
C) are also incorrect as they do not correspond to the accurate conversion of 0 K to °C.

Correct Answer: B

Rationale: Beta radiation is composed of high-energy electrons (β- particles) or positrons (β+ particles) traveling at considerable speeds. In this case, the electrons traveling at around 16,000 km/sec align with the characteristics of beta radiation, making it the correct choice. Alpha radiation consists of helium nuclei, gamma radiation is electromagnetic radiation of high frequency, and delta radiation is not a recognized form of radiation, making them all incorrect choices.