Density of water at room temperature is 1 g/ml. How many molecules are there in a drop of water, if its volume is 0.05 ml ?

Density of water at room temperature = 1 g/ml∴   1  ml  contain  118  moles  of  H2O0.05 ml  will  contain  0.05  × 118  moles∴  1  mole  =  6.022  ×  1023  moleculesTotal  number  of  molecules  in a  drop  of  water=6.023  × 1023 × 0.05  ×  118=1.67  ×  1021