J.R. S. answered 12/04/20
Ph.D. University Professor with 10+ years Tutoring Experience
40.0 ml of solution x 0.870 g/ml = 34.8 g of solution.
Since 22% of this is NH3, we have 0.22 x 34.8 g = 7.656 g NH3
Moles of NH3 present = 7.656 g NH3 x 1 mol NH3/17.0 g = 0.450 moles NH3
Volume = 300 ml = 0.300 L
Concentration (M) of NH3 = 0.450 moles/0.300 L = 1.50 M