Answer :

no. of moles -= given mass/ molar mass

1) 9 g of H2O = 9/18 = 1/2 = 0.5 mole

2) 88g of CO2 = 88/44 = 2moles

3) 1.7 g of NH3 = 1.7/17 = 0.1 mole
number of moles= mass/molar mass
1. 9 g of H2O =9/18=0.5 moles
2.88 gof CO2=88/44=2 moles
3.70 g of NH3=70/17=4.12 moles