设水为1L,则氨气为700L
溶液总质量m（液）=1000g+700L÷22.4L/mol×17g/mol=1531.25g
溶液体积V=1531.25g÷0.9g/Ml=1701Ml=1.7L
n（NH3）=700L÷22.4L/mol=31.25mol
c（NH3）=31.25mol÷1.7L=18.4mol/L