A normal saline drip is a NaCl solution that is isotonic to blood serum so that it does not affect the size of blood cells. If normal saline is 0.89% (w/v), how would you prepare 250. mL of a normal saline solution?

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.

Use a magnet to separate iron, evaporate water, i'm not sure how to separate the other two i'm sorry but good luck

What are the options? physical property can be color, smell, opacity, viscosity, density, infra red spectrum, melting and boiling points, attraction and repulson to magnets, etc.

I’m really not sure what’s the answer. sorry