ati teas 7 science

Correct Answer: A

Rationale: The P wave on an ECG represents atrial depolarization. During the cardiac cycle, the electrical impulse originates in the sinoatrial (SA) node, causing the atria to contract. This depolarization of the atria is reflected as the P wave on the ECG. This occurs before the ventricles depolarize (choice B), repolarize (choice D), or before the atria repolarize (choice C). Therefore, the correct answer is A because the P wave specifically represents atrial depolarization in the cardiac cycle.

Correct Answer: C

Rationale: Step 1: Amphiprotic substances can donate and accept protons, making them capable of acting as both acids and bases. Step 2: When amphiprotic substances react, they can donate or accept protons depending on the reaction conditions. Step 3: This ability allows them to exhibit properties of both acids and bases. Step 4: Therefore, Choice C is correct as it accurately describes the nature of amphiprotic substances. Summary: A: Incorrect - Amphiprotic substances can react with both acids and bases, not just acids. B: Incorrect - Amphiprotic substances can react with both acids and bases, not just bases. D: Incorrect - Amphiprotic substances are not inert; they actively participate in chemical reactions by donating and accepting protons.

Correct Answer: D

Rationale: The correct answer is D, the medium's properties. The speed of a wave in a given medium is determined by the properties of that medium, such as its density and elasticity. This affects how fast the wave can travel through the medium. Amplitude (A) is the height of a wave, which does not directly impact the speed of the wave. Wavelength (B) is the distance between two consecutive points of a wave, and while it can affect the wave's behavior, it does not solely determine its speed. Frequency (C) is the number of wave cycles that pass a point in a given time, which is related to speed but not the sole determinant. Therefore, the correct answer is D as the properties of the medium directly influence the speed of the wave.

Correct Answer: B

Rationale: Platelets are responsible for blood clotting, which is crucial for preventing excessive bleeding when a blood vessel is injured. They adhere to the site of injury and form a plug to stop bleeding. This function is essential for maintaining hemostasis in the body. Platelets do not carry oxygen like red blood cells (Choice A), fight infection like white blood cells (Choice C), or transport nutrients like plasma (Choice D).

Correct Answer: B

Rationale: The correct answer is B. A decomposition reaction involves a single compound breaking down into two or more simpler substances. In choice B, CaCO3 decomposes into CaO and CO2. This reaction follows the general form AB → A + B, making it a clear example of a decomposition reaction. Choices A, C, and D involve synthesis or combination reactions, where simpler substances combine to form a more complex compound, making them incorrect for this question.