Asolution is prepared by dissolving 15.0 g of nh3 in 250.0 g of water. the density of the resulting 7)solution is 0.974 g/ml. the molality of nh3 in the solution is

0.0597 
 Mole fraction NH3 = moles NH3 / total moles in solution  
 moles NH3 = mass / molar mass  
 = 15.0 g / 17.034 g/mol  
 = 0.88059 moles    
 moles H2O = 250 g / 18.016 g/mol  
 = 13.8766 mol    
 total moles = 0.88059 + 13.8766  
 = 14.757 mol    
 fole fraction NH3 = 0.88059 / 14.757   
= 0.0597