How much NaCI must be added to water to make a 100.-g saline solution, 0.90%?
To make a 100g saline solution 0.90% NaCl, you would need:
0.90% of 100g = 0.009 x 100g = 0.9g
Therefore, you would need to add 0.9g of NaCl to the water to make a 100g saline solution with a 0.90% concentration.