Which of the following is an example of a salt?

Correct Answer: C

Rationale: Sodium chloride (NaCl) is an example of a salt. Salts are ionic compounds formed by the reaction of an acid with a base. In this case, sodium chloride is formed by the reaction of sodium hydroxide (a base) with hydrochloric acid (an acid). Sodium hydroxide (NaOH), hydrochloric acid (HCl), and sulfuric acid (Hâ‚‚SOâ‚„) are not salts because they are not formed by the neutralization reaction of an acid and a base, which is a characteristic of salts.

Correct Answer: D

Rationale: Acceleration is defined as the rate of change of velocity with respect to time. The correct formula to calculate acceleration is Acceleration = Time Change in Velocity. This formula specifically represents how much an object's velocity changes over a specified time period, providing a measure of the object's speed change rate. Choices A and B are incorrect as they do not represent the relationship between acceleration and time change in velocity. Choice C is incorrect as it involves time and distance, which are not directly related to acceleration.

Correct Answer: A

Rationale: Mass is the amount of matter in an object and is a scalar quantity, whereas weight is the force of gravity acting on an object and is a vector quantity. Mass remains constant regardless of the location, while weight can vary depending on the strength of gravity at different locations. Answer choice A correctly defines the difference between mass and weight, making it the correct answer. Choice B is incorrect because mass is not a measure of inertia. Choice C is incorrect as mass is typically measured in kilograms, not pounds. Choice D is incorrect as mass is a scalar quantity, and weight is a vector quantity.

Correct Answer: A

Rationale: Proteins are made up of long chains of amino acids, and there are 20 standard amino acids commonly found in proteins. The sequence and arrangement of these amino acids determine the structure and function of a protein. While proteins can vary in size and complexity, the number of amino acids typically ranges from around 10 to 20 in smaller proteins to hundreds or even thousands in larger proteins. Therefore, the range of 10-20 amino acids is the most accurate representation of the number of amino acids that can make up a protein. Choices B, C, and D are incorrect as they provide ranges that are beyond the typical number of amino acids found in proteins and may lead to confusion. The correct answer is A (10-20).

Correct Answer: B

Rationale: The 'lock-and-key' model describes the specificity of the interaction between enzymes and their substrates. In this model, the enzyme's active site acts like a lock that can only be opened by the specific substrate molecule, which serves as the key. This specific binding ensures that enzymes catalyze particular reactions and do not interact with other molecules indiscriminately. Protein folding (option A) is the process by which a protein attains its functional three-dimensional structure but is not directly related to the lock-and-key model. Muscle contraction (option C) and blood clotting (option D) are complex biological processes but are not directly associated with the lock-and-key model of enzyme-substrate interaction.