Chemistry Hesi A2 - Nurselytic

Correct Answer: B

Rationale: The rate of diffusion is inversely proportional to the molar mass of the gas. Helium has the lowest molar mass among the given gases, making it the lightest and fastest gas to diffuse.
Therefore, helium would be expected to diffuse most rapidly compared to carbon monoxide, nitrogen, and oxygen. Carbon monoxide, nitrogen, and oxygen have higher molar masses than helium, so they would diffuse more slowly.
Therefore, the correct answer is helium.

Correct Answer: A

Rationale: Ozone (O3) is a triatomic allotrope of oxygen. It differs from the common diatomic oxygen molecule (O2) by having three oxygen atoms bonded together. Ozone is known for its protective role in the Earth's atmosphere, absorbing most of the Sun's harmful ultraviolet radiation. Water (H2O) is a compound composed of two hydrogen atoms and one oxygen atom. Acidic oxide and carbon dioxide are not triatomic allotropes of oxygen. Carbon dioxide consists of one carbon atom and two oxygen atoms, while acidic oxides refer to compounds where oxygen is bonded with other elements to form oxides, and they are not allotropes of oxygen.

Correct Answer: D

Rationale: Lemon juice is the correct answer as it is acidic in nature. Acids like lemon juice release hydrogen ions when dissolved in water, which causes litmus dye to change color from blue to red. Milk (
Choice
A) is neutral, sea water (
Choice
B) is slightly alkaline, and ammonia (
Choice
C) is a base.
Therefore, these substances do not cause litmus dye to change from blue to red.

Correct Answer: A

Rationale: In the solid state, you would expect a nonmetal to be brittle. Nonmetals generally lack the malleability and ductility of metals, which makes them prone to being brittle and easily fractured under stress. This property is due to the lack of metallic bonding in nonmetals, which results in a more rigid and less flexible structure.


Choice B, 'lustrous,' is incorrect because nonmetals typically do not exhibit a shiny or reflective surface like metals do.
Choice C, 'malleable,' is also incorrect as nonmetals lack the ability to be hammered or rolled into thin sheets like metals.
Choice D, 'conductive,' is incorrect since nonmetals are generally poor conductors of electricity compared to metals.

Correct Answer: B

Rationale: Noble gases are non-polar molecules without a permanent dipole moment. The only intermolecular force applicable to noble gases is the London dispersion force, also known as Van der Waals forces. This force is a temporary attractive force resulting from the formation of temporary dipoles in non-polar molecules. Dipole-dipole interactions, Keesom interactions, and hydrogen bonding involve significant dipoles or hydrogen atoms bonded to electronegative atoms, which do not apply to noble gases.