HESI A2 Chemistry

HESI A2 Chemistry Related

Review HESI A2 Chemistry related questions and content

What is the name of the compound CH₃-CH₂-CH₂-CH₃?

  • A. Cyclobutane
  • B. Butane
  • C. Butene
  • D. Butyne
Correct Answer: B

Rationale: The compound CH₃-CH₂-CH₂-CH₃ is named butane. Butane is a straight-chain alkane comprising four carbon atoms connected by single bonds. The prefix 'but-' denotes the presence of four carbon atoms, while the suffix '-ane' indicates it is an alkane with single bonds between the carbon atoms. Choice A, Cyclobutane, is incorrect as it refers to a cyclic hydrocarbon with four carbon atoms in a ring structure. Choice C, Butene, is incorrect because it is an alkene with a double bond between two carbon atoms, not a saturated hydrocarbon like butane. Choice D, Butyne, is also incorrect as it is an alkyne with a triple bond between two carbon atoms, unlike the single bonds in butane.

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Among the following elements, which is a nonmetal?

  • A. Mercury
  • B. Magnesium
  • C. Sulfur
  • D. Potassium
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.

What are proteins made up of?

  • A. Fatty acids
  • B. Amino acids
  • C. Nucleotides
  • D. Sugars
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.

If fifty-six kilograms of a radioactive substance has a half-life of 12 days, how many days will it take the substance to decay naturally to only 7 kilograms?

  • A. 8
  • B. 12
  • C. 36
  • D. 48
Correct Answer: C

Rationale: To decay from 56 kg to 7 kg, the substance needs to go through 3 half-lives (56 kg · 2 · 2 · 2 = 7 kg). Since each half-life is 12 days, the total time required is 12 days per half-life x 3 half-lives = 36 days. Choice A is incorrect because it does not consider the concept of half-lives. Choice B is incorrect because it represents the duration of a single half-life, not the total time required for the decay. Choice D is incorrect as it does not account for the multiple half-lives needed for the substance to decay from 56 kg to 7 kg.

What is a pentose sugar?

  • A. A 6 carbon sugar
  • B. A 4 carbon sugar
  • C. A 5 carbon sugar
  • D. A 7 carbon sugar
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.

How many protons does Potassium have?

  • A. 18
  • B. 19
  • C. 20
  • D. 21
Correct Answer: B

Rationale: Potassium, with the atomic symbol K, has 19 protons, which is equal to its atomic number. The number of protons determines the element's identity, and in the case of Potassium, it is 19. Choice A (18) is incorrect as it does not correspond to Potassium's proton number. Choice C (20) and Choice D (21) are also incorrect as they do not match the actual number of protons in Potassium.

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