HESI A2 Chemistry - Nurselytic

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: Proteins are made up of amino acids. Amino acids are the building blocks of proteins, essential for various biological processes in the body such as enzyme function, transport, and structural support. Fatty acids (
Choice
A) are components of lipids, not proteins. Nucleotides (
Choice
C) are the building blocks of nucleic acids like DNA and RNA, not proteins. Sugars (
Choice
D) are carbohydrates and are not the primary components of proteins.

Correct Answer: C

Rationale: Sulfur is a nonmetal as it is located on the right side of the periodic table. Nonmetals generally exhibit properties such as being brittle, poor conductors of heat and electricity, and having lower melting points compared to metals. Mercury (
A), Magnesium (
B), and Potassium (
D) are all metals due to their metallic properties. Mercury is a liquid metal at room temperature, Magnesium is a solid metal, and Potassium is a solid metal as well.
Therefore, the correct answer is C, Sulfur.

Correct Answer: B

Rationale: The chemical equation AB → A + B represents a decomposition reaction. In a decomposition reaction, a single compound breaks down into two or more simpler substances. In this specific reaction, compound AB is decomposed into its elements, A and B, making it a decomposition reaction.
Choice A, Synthesis, involves the combination of two or more substances to form a more complex product, which is not the case here.

Choices C and D, Single replacement and Double replacement, involve the exchange of ions between compounds or elements, which is not happening in the given reaction.

Correct Answer: B

Rationale: The correct answer is B: '2'. In a single covalent bond, two electrons are shared between two atoms. Each atom contributes one electron to form the bond, resulting in the sharing of a total of two electrons.
Choice A is incorrect because a single covalent bond involves the sharing of two electrons, not one.

Choices C and D are incorrect as they do not represent the correct number of electrons shared in a single covalent bond.