how could water be boiled at room temperature

HESI A2

HESI A2 Chemistry Questions

1. How can water be boiled at room temperature?

A. By lowering the pressure
B. By increasing the pressure
C. By decreasing the volume
D. By raising the boiling point

Correct answer: A

Rationale: The boiling point of water is directly affected by pressure. By lowering the pressure, water can boil at a lower temperature, even at room temperature. This occurs because at lower pressures, the molecules of water have less resistance to escaping into the vapor phase, thus enabling boiling to occur at lower temperatures. Choices B, C, and D are incorrect because increasing the pressure, decreasing the volume, or raising the boiling point would actually require higher temperatures to boil water rather than achieving boiling at room temperature.

2. Which best defines the molarity of an aqueous sugar solution?

A. Grams of sugar per milliliter of solution
B. Moles of sugar per milliliter of solution
C. Grams of sugar per liter of solution
D. Moles of sugar per liter of solution

Correct answer: D

Rationale: The molarity of a solution is defined as the number of moles of solute per liter of solvent. In the case of an aqueous sugar solution, the molarity would be expressed as moles of sugar per liter of solution. This is because molarity is a measurement of the concentration of a solute in a solution based on the number of moles present in a given volume of the solution. Therefore, the correct answer is D. Choices A, B, and C are incorrect because the molarity is specifically defined in terms of moles of solute per liter of solution, not in grams per milliliter or grams per liter. Molarity is a unit of concentration that relates the amount of solute to the volume of the solution, not the mass of the solute.

3. What is the correct formula for iron III oxide?

A. IO
B. FeS
C. Fe₂O₃
D. OFe₂₃

Correct answer: C

Rationale: The correct formula for iron III oxide is Fe2O3. In this formula, Fe represents iron and O represents oxygen. Iron III oxide consists of two iron (Fe) ions combined with three oxygen (O) ions. Thus, the correct formula is Fe2O3. Choice A (IO) is incorrect as it does not represent the correct combination of iron and oxygen ions. Choice B (FeS) is incorrect as it represents iron sulfide, not iron III oxide. Choice D (OFe₂₃) is incorrect as it does not follow the correct chemical nomenclature for iron III oxide.

4. If electrons are not shared equally in a covalent bond, the bond is what?

A. Polar
B. Non-polar
C. Ionic
D. Hydrogen

Correct answer: A

Rationale: A polar covalent bond occurs when electrons are shared unequally between atoms. In this type of bond, one atom has a stronger pull on the shared electrons, leading to a partial positive and partial negative charge distribution within the molecule. Choice B, non-polar, is incorrect because in non-polar covalent bonds, electrons are shared equally between atoms. Choice C, ionic, is incorrect as ionic bonds involve a transfer of electrons rather than sharing. Choice D, hydrogen, is incorrect as it does not describe the nature of a covalent bond.

5. What is the mass number of an atom with 6 protons, 6 neutrons, and 6 electrons?

A. 12
B. 18
C. 6
D. 8

Correct answer: A

Rationale: The mass number of an atom is the sum of protons and neutrons. In this case, the atom has 6 protons and 6 neutrons, thus the mass number is 6 + 6 = 12. Therefore, choice A (12) is the correct answer. Choices B (18), C (6), and D (8) are incorrect because the mass number is determined by the sum of protons and neutrons, not the number of electrons or a different combination of particles.