What volume of physiological saline solution (90% by weight NaCl, in water) would give you a gram of salt when evaporated?
Basically you need to assume that there are 100g of solution.
Therefore, if you have 90% NaCl in water, then you would have 90g of NaCl and 10g of water.
Using the density equation, d= g/mL
Plug in the value for grams NaCl and then the density which is about 1.694.
1.694=90g/ ml
then,
mL= 90g/1.694
53.1 mL NaCL
That is how I would have done it.