number of molecule in 1 1/2 of water (density of water 1.0 g )

 Solution: 

Density= Mass/Volume

Mass= Density  x  Volume

          = 1.00 x 1.5

          = 1.5 g

Mass of 1 mole of water=18g

18g of water contains 6.023 x 10²³ molecules

1.5g of water contains= 6.023 x 10²³ x 1.5

                                                  18

                                       = 0.5 x 10²³

Therefore, 1.5g of water contains  0.5 x 10²³ molecules.