Nursing Elites

1. Which of the following represents a hydride ion?

• A. H⁻
• B. H⁺
• C. OH⁻
• D. HCl

Correct answer: A

Rationale: The hydride ion is denoted by H⁻, indicating that it has gained an extra electron to complete its valence shell, resulting in a full octet and a net charge of -1. This ion is commonly found in metal hydrides and plays a significant role in various chemical reactions. Option B, H⁺, represents a proton with a positive charge. Option C, OH⁻, represents the hydroxide ion, consisting of oxygen and hydrogen. Option D, HCl, is a compound composed of hydrogen and chlorine ions, not a hydride ion.

2. What is a balanced equation?

• A. A description where reactants and products are not equal
• B. An equation where the number of each type of atom is the same on both sides
• C. A chemical formula showing only reactants
• D. An equation without coefficients

Correct answer: B

Rationale: A balanced equation is one where the number of each type of atom is the same on both sides, fulfilling the law of conservation of mass. This principle ensures that the total number of atoms of each element is equal in both reactants and products, signifying that no atoms are created or destroyed, but rather rearranged. Choice A is incorrect because a balanced equation has equal numbers of atoms in the reactants and products. Choice C is incorrect as a balanced equation includes both reactants and products. Choice D is incorrect because coefficients are essential in balancing equations by adjusting the number of atoms present.

3. How many amino acids are essential for human life?

• A. 22
• B. 20
• C. 18
• D. 24

Correct answer: B

Rationale: There are 20 essential amino acids required for human life. These amino acids cannot be synthesized by the body and must be obtained through the diet. They play crucial roles in various physiological functions and are necessary for protein synthesis and overall health. Choice A is incorrect because there are not 22 essential amino acids. Choice C is incorrect as there are more than 18 essential amino acids. Choice D is incorrect as there are not 24 essential amino acids for human life.

4. In what type of covalent compounds are dispersion forces typically found?

• A. Polar
• B. Non-polar
• C. Ionic
• D. Hydrogen

Correct answer: B

Rationale: Dispersion forces, also known as London dispersion forces, are the weakest intermolecular forces that occur in non-polar covalent compounds. These forces result from temporary shifts in electron density within molecules, creating temporary dipoles. As a result, non-polar molecules, which lack a permanent dipole moment, can experience these dispersion forces. Polar compounds exhibit stronger intermolecular forces such as dipole-dipole interactions or hydrogen bonding, while ionic compounds involve electrostatic interactions between ions. Therefore, the correct answer is non-polar (choice B). Choices A, C, and D are incorrect because dispersion forces are typically found in non-polar covalent compounds, not polar, ionic, or hydrogen-bonded compounds.

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.

Similar Questions