What is the no. of molecules in a drop of water weighing 0.05g.?
One drop of water has the weight = 0.05 g.
The molar mass of water (H2O) is 18.0 grams/mol (1.008 + 1.008 + 16.0).
This means there is one mole of water in 18.0 grams. One mole is 6.02 × 1023 molecules.
Then the number of atoms in 0.5 g:
0.05 grams ÷ 18.0 grams × (6.02 × 1023molecules)= 1.67× 1022 molecules