Question

If a healthy man drinks one litre of water on occasion A and one litre of $0.9$ saline on occasion B, what shall we expect in two hours?

Answer 1

When a healthy man drinks one litre of water on occasion A it releases normal volume of urine and $N{a}^{+}$ concentration. But when he drinks one litre of $0.9$ saline which is solution of $NaCl$ , sodium concentration in blood increases and water follows it by osmosis. So, because of increase in absorption of water, volume of urine decreases and there will be no effect on $N{a}^{+}$ concentration in volume of urine.