If normal saline is 0.9% saline, how much sodium chloride is in 25 ml of it?

To determine how much sodium chloride is in 25 ml of normal saline (which is 0.9% saline), you can use the percentage concentration to calculate the amount of sodium chloride present in that volume.

A 0.9% solution means that there are 0.9 grams of sodium chloride in every 100 ml of solution. First, convert 0.9 grams to milligrams since the answer options are in milligrams.

0.9 grams is equivalent to 900 mg. Therefore, in 100 ml of solution, there are 900 mg of sodium chloride.

Next, to find out how much sodium chloride is in 25 ml, you set up a proportion based on the known concentration:

(900 mg / 100 ml) = (X mg / 25 ml)

By cross-multiplying, you get:

900 mg * 25 ml = 100 ml * X mg

22,500 mg ml = 100 ml * X mg

Now, divide both sides by 100 ml to isolate X:

X = 225 mg

This calculation indicates that there are 225 mg of sodium chloride in 25 ml of normal saline. Thus, the correct answer is indeed 225 mg, aligning