Question

what is the no. of molecules in a drop of water weighing 0.2 g ?

Answer 1

18 g of water = 6.022×10²³ molecules

1 g of water = (6.022/18)×10²³ molecules

0.2 g of water = (6.022×0.2/18)×10²³ = 0.0669×10²³ = 6.69×10²¹ molecules