Which of them is TRUE about Na –  - K+ pump
In Na+-K+ exchange, 3 Na+ goes out and 2K+ goes into the cell with the utilization of ATP. 
Hence it is a primary active transport. Due to the net flow of Na+ outwards, there is a potential difference that occurs. Both Na+  and K+  are pumped against a concentration gradient by using ATP.
K+ is pumped against the gradient
2K+ are exchanged with 5Na+
Hypercalcemia causes arrest in Na+ K+ pump
Increase in intracellular Na+ increases action potential