Correct Answer: A

Rationale: Tachypnea is an early sign of congestive heart failure that nurses should recognize. Tachypnea refers to rapid breathing, which can be an indication of the body's attempt to compensate for decreased cardiac output in congestive heart failure. Bradycardia (choice B) is a slow heart rate and is not typically associated with congestive heart failure. Inability to sweat (choice C) and increased urinary output (choice D) are not specific early signs of congestive heart failure and are not typically recognized as such.

Correct Answer: D

Rationale: The correct answer is D. Infants have a higher extracellular fluid requirement per unit of body weight, making them more susceptible to dehydration and electrolyte imbalances during illnesses such as diarrhea. Choice A is incorrect as cellular metabolism instability does not directly relate to the infant's condition described. Choice B is inaccurate as the proportion of water in the body is not the primary issue causing the infant's symptoms. Choice C is incorrect as renal function being immature does not explain the sudden change in the infant's health status; it is more related to fluid balance and dehydration.

Correct Answer: A

Rationale: The correct answer is A. Reading stories to the child about famous athletes would be the most successful guidance for a child with a 'slow-to-warm-up' temperament. This approach allows for a less active and more acceptable way of engaging with the child, aligning better with the child's temperament. Choices B, C, and D involve more active and potentially overwhelming activities for a child with such a temperament, which may not be as effective in stimulating and engaging the child.

Correct Answer: B

Rationale: Chest tubes are necessary after open-heart surgery to facilitate the drainage of air and fluid from the chest cavity. These tubes help prevent complications such as pneumothorax (accumulation of air in the pleural space) or cardiac tamponade (build-up of fluid in the pericardial sac), which can be serious postoperative issues. Options A, C, and D are incorrect because chest tubes are primarily used for draining purposes and not for increasing tidal volumes, maintaining positive intrapleural pressure, or regulating pressure on the pericardium and chest wall.

Correct Answer: D

Rationale: Explaining the use of prescribed medications is crucial because it helps ensure proper management of the child's condition after discharge. While teaching the parents about signs of infection and providing instructions on wound care are important aspects of postoperative care, they are not as critical as ensuring the correct understanding and administration of prescribed medications. Scheduling follow-up appointments is also important but does not directly impact the immediate post-discharge care and medication adherence.