Correct Answer: C

Rationale: In a 5-year-old child who is unconscious with a respiratory rate of 8 breaths/min and a heart rate of 50 beats/min, the priority is to initiate chest compressions, artificial ventilations, and rapid transport. These vital interventions are crucial in cases of severe respiratory and cardiovascular compromise. Choice A is incorrect because administering 100% oxygen alone may not address the underlying issues of inadequate ventilation and circulatory support. Choice B is not the most appropriate initial intervention in this scenario; chest compressions should precede positive pressure ventilations. Choice D is incorrect as back blows and chest thrusts are indicated in choking emergencies, not in this case of respiratory and cardiovascular compromise.

Correct Answer: B

Rationale: In Addison's disease, adrenal insufficiency leads to decreased aldosterone production. This results in impaired sodium retention and potassium excretion, leading to hyperkalemia. Therefore, the correct answer is hyperkalemia (choice B). Hypernatremia (choice A) is less likely because of the loss of sodium in Addison's disease. Hyperglycemia (choice C) and hypercalcemia (choice D) are not typically associated with Addison's disease and are less likely to be present in this condition.

Correct Answer: C

Rationale: Abnormal heart sounds could indicate a congenital heart defect, which is common in infants with Down syndrome.

Correct Answer: D

Rationale: Recognizing signs of hypoglycemia is crucial for managing type 1 diabetes mellitus and preventing complications.

Correct Answer: B

Rationale: The correct answer is B: Rolls over. At 6 months, most infants can roll over, increasing the risk of falls. It is important to emphasize to the parent the need for careful supervision to prevent accidents. While choices A, C, and D are also milestones in infant motor development, rolling over at this age poses a higher risk of accidents due to the increased mobility and potential for falls.