Nursing Elites

1. What is the correct formula for potassium chloride?

• A. NaCl
• B. KCl
• C. KCl
• D. ClK

Correct answer: B

Rationale: The correct formula for potassium chloride is KCl. In chemical formulas, the symbol for the cation (positive ion) comes first followed by the symbol for the anion (negative ion). Potassium is represented by the symbol K, while chloride is represented by the symbol Cl. Therefore, the formula for potassium chloride is KCl. Choice A (NaCl) is the formula for sodium chloride, not potassium chloride. Choice C is a duplicate of choice B, and choice D (ClK) is an incorrect arrangement of the symbols for potassium and chloride.

2. How many neutrons are in an atom of uranium-235?

• A. 92
• B. 125
• C. 143
• D. 235

Correct answer: A

Rationale: The correct answer is A: '92'. To determine the number of neutrons in an atom, you subtract the atomic number (number of protons) from the atomic mass number. For uranium-235, the atomic number is 92, and the atomic mass number is 235. Subtracting 92 from 235 gives us 143 neutrons in an atom of uranium-235. Therefore, options B, C, and D are incorrect as they do not represent the correct number of neutrons in an atom of uranium-235.

3. What is the SI unit of energy?

• A. ohm
• B. joule
• C. henry
• D. newton

Correct answer: B

Rationale: The SI unit of energy is the 'joule'. The joule is defined as the work done when a force of one newton acts over a distance of one meter. It is the standard unit used to measure energy in the International System of Units (SI). Therefore, the correct answer is 'joule.' Choice A, 'ohm,' is the SI unit of electrical resistance, not energy. Choice C, 'henry,' is the SI unit of inductance, not energy. Choice D, 'newton,' is the SI unit of force, not energy. Hence, they are all incorrect in the context of measuring energy.

4. 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.

5. What are the products of the combustion of a hydrocarbon?

• A. Water and carbon dioxide
• B. Water and oxygen
• C. Hydrogen and carbon monoxide
• D. Carbon dioxide and oxygen

Correct answer: A

Rationale: When a hydrocarbon undergoes combustion, it reacts with oxygen to produce water and carbon dioxide as the main products. The general chemical equation for the combustion of a hydrocarbon is hydrocarbon + oxygen → carbon dioxide + water. Therefore, the correct answer is 'Water and carbon dioxide.' Choices B, C, and D are incorrect because water and carbon dioxide are the primary products of hydrocarbon combustion, not water and oxygen, hydrogen and carbon monoxide, or carbon dioxide and oxygen.

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