Correct Answer: A

Rationale: The correct answer is Agranulocytosis. Methimazole, used to treat hyperthyroidism, can lead to agranulocytosis, a severe decrease in white blood cells. This condition increases the risk of infections and requires immediate medical attention. Hypoglycemia (choice B) is not a common adverse effect of methimazole. Bradycardia (choice C) is unlikely as methimazole tends to have minimal effects on heart rate. Hypercalcemia (choice D) is not associated with methimazole use.

Correct Answer: C

Rationale: To deliver 1,000 units/hour from a solution with 25,000 units in 500 ml, the rate should be set to 20 ml/hour. This is calculated by determining that the solution has 50 units/ml (25,000 units / 500 ml = 50 units/ml) and then dividing the required 1,000 units/hour by 50 units/ml, resulting in 20 ml/hour. Therefore, the nurse should program the infusion pump to deliver heparin at 20 ml/hour. Choices A, B, and D are incorrect as they do not align with the calculated rate of 20 ml/hour.

Correct Answer: B

Rationale: The ABG results show a low pH (acidosis) and increased pCO2, indicating respiratory acidosis. In respiratory acidosis, the lungs cannot remove enough CO2, leading to its accumulation in the blood. This often occurs in conditions like COPD and is consistent with the patient's smoking history. Metabolic acidosis (choice A) is characterized by low pH and low HCO3 levels. Metabolic alkalosis (choice C) is marked by high pH and high HCO3 levels. Respiratory alkalosis (choice D) presents with high pH and low pCO2.

Correct Answer: A

Rationale: Elevated serum amylase is the most indicative laboratory result of acute pancreatitis. In this condition, the pancreas becomes inflamed, leading to the leakage of amylase and lipase into the bloodstream. Elevated serum amylase levels are a classic finding in acute pancreatitis. Choices B, C, and D are not typically associated with acute pancreatitis. Decreased serum bilirubin, increased blood urea nitrogen (BUN), and decreased alkaline phosphatase levels are not specific markers for acute pancreatitis.

Correct Answer: A

Rationale: The correct answer is A: 'There is an extra chromosome on the 21st pair.' Down syndrome is caused by the presence of an extra copy of chromosome 21, known as trisomy 21. This additional genetic material leads to the characteristics associated with Down syndrome. Choices B, C, and D are incorrect because Down syndrome is not due to a missing chromosome or having two pairs of the 21st chromosome; it results from the presence of an extra chromosome on the 21st pair.