The number of molecules in one litre of water is (density of water = 1g/mL)

Density of liquid water = 1g/ccGMW of water = 18g18g water contaion---- 6.023×102318g = 18ml( density = 1gl ml)18ml of water contain 6.02×1023 molecules1000ml of H2O contain 'X' molecules    X = 3.3 ×1025