HESI A2
HESI A2 Chemistry Questions
1. What is the main component of air?
- A. Oxygen
- B. Nitrogen
- C. Carbon dioxide
- D. Argon
Correct answer: B
Rationale: Nitrogen is the main component of air, constituting approximately 78% of the Earth's atmosphere. Oxygen, carbon dioxide, and argon are also present in smaller amounts, but nitrogen is the most abundant gas in the air. Therefore, the correct answer is B. Choice A, oxygen, is essential for respiration but makes up only about 21% of the atmosphere. Choice C, carbon dioxide, is vital for photosynthesis but exists in trace amounts in the air. Choice D, argon, is a noble gas found in relatively small quantities in the atmosphere.
2. How many neutrons are in an atom of helium-4?
- A. 2
- B. 3
- C. 4
- D. 6
Correct answer: A
Rationale: The atomic number of helium is 2, indicating it has 2 protons. Helium-4, the most common isotope of helium, has 2 neutrons in addition to its 2 protons. Therefore, the correct answer is 2 neutrons in an atom of helium-4. Choice B, C, and D are incorrect as they do not match the correct composition of helium-4, which consists of 2 protons and 2 neutrons.
3. 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.
4. Beta radiation is the product of the decomposition of which particle?
- A. Proton
- B. Neutron
- C. Electron
- D. Photon
Correct answer: B
Rationale: Beta radiation is the result of the decomposition of a neutron. During beta decay, a neutron in an atom's nucleus is transformed into a proton, an electron (beta particle), and an antineutrino. Therefore, the correct answer is 'Neutron.' Choice A, 'Proton,' is incorrect because beta decay does not involve the decomposition of a proton. Choice C, 'Electron,' is incorrect because electrons are actually produced during beta decay. Choice D, 'Photon,' is incorrect as beta radiation does not involve the decomposition of photons.
5. What type of reactions take place in the nucleus to achieve stable nuclear configurations?
- A. Chemical
- B. Nuclear
- C. Physical
- D. Mechanical
Correct answer: B
Rationale: Nuclear reactions occur within the nucleus to achieve stable nuclear configurations. These reactions involve changes in the composition of atomic nuclei, leading to the formation of more stable elements. Chemical reactions occur in the electron cloud surrounding the nucleus, while physical and mechanical processes do not directly impact the stability of nuclear configurations. Therefore, the correct answer is 'Nuclear.'
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