Resting Membrane Potential and Action Potential

Concerning the phases of the action potential and the underlying ionic mechanisms, all of the following are true EXCEPT:

The resting membrane potential of a typical neuron is approximately −70 mV. Which ion gradient is primarily responsible for maintaining this potential?

A 28-year-old male from Mumbai presents to the emergency department with acute-onset muscle weakness and paresthesias in both lower limbs. He reports consuming a large quantity of raw cashew nuts 2 hours prior. On examination, he has flaccid paralysis of bilateral lower limbs with preserved sensation. Serum potassium is 7.2 mEq/L (normal 3.5–5.0). ECG shows peaked T waves and prolonged PR interval. Which of the following best explains the neurophysiological basis of his muscle weakness?

A 52-year-old woman from Delhi with chronic kidney disease (eGFR 18 mL/min) presents with severe muscle cramps, weakness, and an irregular heartbeat. Serum potassium is 6.8 mEq/L. An ECG is performed and shows tall, peaked T waves, a widened QRS complex (140 ms), and a prolonged PR interval (220 ms). She is given intravenous calcium gluconate immediately. Which of the following best describes the mechanism by which calcium gluconate reverses the cardiac manifestations of hyperkalemia?

Which ion is the most common determinant of the resting membrane potential in excitable cells?