HESI A2 Chemistry Questions

Correct Answer: B

Rationale: The correct answer is B: Oxygen. During photosynthesis, plants use carbon dioxide and water to produce glucose and oxygen. Oxygen is released as a byproduct of this process through the stomata in plant leaves. Carbon dioxide (A) is actually used up during photosynthesis, not released. Nitrogen (C) and Helium (D) are not involved in the process of photosynthesis.

Correct Answer: A

Rationale: The correct answer is A: By lowering the pressure. When pressure is decreased, the boiling point of water also decreases, allowing it to boil at room temperature. Lower pressure reduces the amount of energy needed for water molecules to escape into the gas phase. Increasing pressure (Choice B) raises the boiling point, making it harder to boil at room temperature. Decreasing the volume (Choice C) is not directly related to the boiling point of water. Raising the boiling point (Choice D) would require increasing pressure, contradicting the premise of boiling at room temperature.

Correct Answer: B

Rationale: The correct answer is B: Na. Sodium's chemical symbol is Na because it is derived from its Latin name "natrium." N represents nitrogen, Cl represents chlorine, and H represents hydrogen, making them incorrect choices. Remember to consider the element's name origins for accurate symbol identification.

Correct Answer: B

Rationale: The correct answer is B: Fluorine. Fluorine is the most electronegative element because it has the highest electronegativity value on the periodic table. Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. Fluorine has the highest electronegativity value of 3.98, indicating its strong ability to attract electrons. Oxygen (A) is also highly electronegative but has a lower value than fluorine. Nitrogen (C) is less electronegative than oxygen. Sodium (D) is a metal and has low electronegativity compared to the nonmetals listed.

Correct Answer: B

Rationale: The correct answer is B: periods. Periods are the horizontal rows in the periodic table that represent the energy levels of the elements. They indicate the number of electron shells present in an element. Groups (A) are the vertical columns, representing elements with similar chemical properties. Families (C) are also vertical columns that share similar characteristics. Sets (D) is a generic term and not specific to the periodic table structure. Therefore, the correct term for the horizontal rows of the periodic table is periods.