Question

what volume of physiological saline solution (0.90% by weight NaCl, in water) would give you a gram of salt when evaporated?

Answer 1

0.9%NaCl w/v is 0.9g NaCl/100 mL (9g NaCl/L).

1000 mL x (1g/9g) = 111.11 mL.
(Note that 1g/111.11 mL) = 0.009 g/mL or 0.9g/100 mL or 0.9%.