The number of neutrons in a drop of water (20 drops = 1 mL) at 40C

Mass of a drop of water = 0.05  ×  1 g=0.05 gNumber of moles of water = 0.0518Number of water molecules = 0.0518 ×  6.023  × 10231 water molecule contain 8 neutrons∴   0.0518 × 6.023  × 1023  molecule  contain                                                   0.0518 × 6.023  × 1023  neutrons                                                 = 0.1338  × 1023  =1.338  ×  1022