(i) 18mL water:
As dH2O=1g/mL So WH2O=18g
nH2O=1818=1
Molecules =1×NA
(ii) 0.18g of water:
nH2O=180.18=0.01
H2O molecules=0.01×NA
(iii) (VH2O(g))STP=0.00224L
nH2O=22.4V=22.40.00224=0.0001
Molecules =0.0001×NA
(iv) nH2O=10−3
H2O molecules=10−3×NA